Being the main character of the Light Novel series, Ichika has encountered many people along the series, be it with family, friends or enemies.
- Chifuyu Orimura - His older sister, homeroom teacher in Class One and 1st year dorm supervisor. Originally a legendary pilot of the 1st generation IS, she took care of him when their parents abandoned them. Despite the harsh treatment he gets from her, Ichika still loves her deeply. She was the one who transferred him to the IS Academy so that he would be safe from the government. Although he does not remember much, it was his sister who came to save him when he was young. He regretted this though because it cost Chifuyu her title, showing much respect he has for pride. As seen or stated, Ichika is willing to give his life to protect his sister at all costs. Both each have a desire to protect one another, mostly because each of them acknowledge one another as their only family.
- Madoka Orimura - His younger twin sister. She holds a grudge on her older sister, Chifuyu. She has the same appearance like Chifuyu. She is the IS pilot of Silent Zephyrs from Phantom Task. Both faced clashes against each other. When she revealed her true identity to Ichika in the end of Volume 6, he begins to question the forbidden topic about family. It can be assume that she's a least aware that Ichika doesn't know who she is given the fact that she introduced herself to him.
- Dan Gotanda - His friend from middle school. He is often mentioned by Ichika that he wanted to switched places with him to enjoy "paradise" in the IS Academy.
- Ran Gotanda - Dan's younger sister. She has a crush on him.
- Kazuma Mitarashi - Another friend from middle school. He appears in Volume 5.
- Tabane Shinonono - Houki's older sister. Tabane calls him affectionately as Ikkun (Short for Ichika-kun), and he has mutual respect for her, though he too is somewhat overwhelmed by her explosive energy.
- Houki Shinonono - His 1st childhood friend and a classmate in Class One. They used to train in kendo when they were young, about six years before the current storyline. Ichika agreed to become her boyfriend if she could win the national kendo tournament of their grade. He told her that he was glad to be her roommate, as he was worried about sharing the same room with a total stranger.
- Ichika, due to his nature, sees Houki in the light of an extremely strong childhood friend of his. He is willing to do things for her that he probably might not do for others. However, before the events of the Shinonono festival (at the end of episode 12 season one), they had practically dated and nearly kissed, implying that he may have some sort of emotions regarding Houki. Of course, Ichika's kiss was comically obstructed by Cecilia, Rin, Charlotte and Laura.
- Throughout the series, there are several occasions implying that Ichika's love interest is Houki. During the episode of "Heart Painkiller" (Infinite Stratos 2, episode 2) dreaming upon the grassland and saw Houki standing by the well. As well, during the episode of "Lovely Style" (Infinite Stratos 2, episode 5) he is well aware of attractiveness of the heroines however during Houki's turn there was a moment where they felt "spark" between them but they were interrupted by Yamada-sensei. Another example could be seen in Volume 8, while Ichika was annoyed by the other girls delusions of him but he seems more jealous by how much better Houki treated the fake Ichika than she ever treated the real him.
- Houki loves Ichika to the point she managed to muster up enough courage to confess to him at the Shinonono festival. However, right when the words "I love you" were said, fireworks exploded, rendering her words inaudible. Her emotional state is also somewhat dependent on her relationship with Ichika, as shown when Akatsubaki's One-Off Ability was activated after excessively thinking about him. Additionally, when he was injured for saving her life by taking a blast meant for her, she was depressed enough that she nearly stopped piloting her IS altogether.
- Cecilia Alcott - His classmate in Class One and the IS Representative Candidate of England. She challenged him to a representative duel as she did believed it to be bias. After giving her a hard time in the duel, she soon starts to see him as a true man and falls in love with him, calling him affectionately as "Ichika-san" much to his confusion and Houki's displeasure.
- Ichicka sees Cecilia as a fellow student and a good friend on most occasions. Of course, the comical and awkward scenes that have involved her before may imply something beyond the boundaries of friendship. Of course, this is completely unconfirmed. They are on relatively good terms, which most likely means that Ichika does not care about the prior incident when they dueled for the position of "Class Representative". Ichika even gave her a massage (to make up for not being able to feed her), something he hasn't offer to any of the other girl before, since neither Houki or Lingyin knew about.
- Cecilia is in, how you would say, love with Ichika to the point of fantasization. While it has happened with all the main heroines of the series, it is undeniable that Cecilia is no exception. Her love for him is a little shallow, but it is love nonetheless, and she puts in as much effort as the rest of the girls.
- Lingyin Huang - His 2nd childhood friend who is the IS Representative Candidate of China and Class Two. She's has been in love with Ichika since he protected her against four school bullies.
- Ichika sees Rin as a really good childhood friend, and this is shown when she was already first introduced. He addresses Rin without any other proper honorifics, and that already shows his good relationship with her. When they were eating together in the cafeteria in the time she had first been introduced, they had already engaged in a very deep and long-winding conversation.
- Rin has loved Ichika for quite some time already, and this was shown when she mentioned the promise they had made to each other when they were much younger. Notably, she and Cecila Alcott share the similar trait of a yandere girlfriend. This is first shown during the events when Charlotte and Ichika went to the mall by themselves.
- While Rin meant for them to become a couple, Ichika had interpreted the promise (with his usual blockheadedness) as getting free sweet and sour pork every day on Rin's behalf. In fairness to Ichika though, the promise was phrased as "If I become a better cook, would you eat my sweet and sour pork every day?".
- Charlotte Dunois - The IS Representative Candidate of France. She was sent as a spy by her father to figure out how Ichika can pilot an IS. After her transfer, she became Ichika's roommate where he later discovers her true gender. Upon learning Charlotte's father and his corporation used her to spy on him, Ichika decides to help and protect her, being reminded of his own history related to his parents.
- When they first met, Ichika was under the impression that all the other students were under. That impression was that Charlotte was a male student known as Charles. During that time frame, Ichika was on extremely close terms with Charles/Charlotte due to his lack of male contact. During the very first day, they had already established a very close friendship.
- After the discovery of Charlotte's/Charles' true gender, Ichika's opinion and friendship towards of her was completely unwavered. Although some events happened between them that were undeniably awkward, they have maintained an extremely good relationship. Ichika even gave Charlotte a nickname for just the two of them (Charl).
- The two are extremely good partners during IS battles for some reason, as shown when they coordinated their attacks extremely well during the match with Laura and Houki. Additionally, Charlotte was able to transfer energy over to Ichika's IS, which is something initially fairly (if not highly) difficult to do. This already can prove how close they are.
- While Ichika views Charlotte as a very good friend and a powerful companion, Charlotte has undeniably fallen in love with the dense Ichika. Her very mannerisms are extremely flustered when around him, and this merely proves that she has very intense feelings for him. While Charlotte is no doubt the gentlest and most forgiving of the harem, she has also shown herself to be extremely scary. This is proven when she is mad at Ichika for whatever reason, and Ichika's inner monologue has described her smile as more scary and demonic rather than the kind and angelic one it usually was.
- Laura Bodewig - The IS Representative Candidate of Germany. Laura comes to the IS Academy to punish Ichika as she blames him for his sister withdrawing from the IS International Fighting Tournament, Mondo Grosso in order to save him when he was kidnapped in the past and denying Chifuyu the right to win.
- Ichika first had a fairly negative impression of Laura, as she had practically attempted to nearly kill Rin and Cecila in what was supposed to be a mock battle. However, after discovering that she looked up to Chifuyu greatly, and also had similar issues to any other normal person, he treated her with kindness and friendship regardless. He trusts her like he would trust any of the other girls at school anyway.
- Laura's first impression of Ichika was far more negative than the latter's. Believing Ichika to be a hindrance for Chifuyu's image in Laura's eyes, Laura did not like him at all, However, after Ichika saved her from the mutated IS, they seemed to have shared a brief moment of conversation before she had fallen unconscious. When Laura saw that Ichika's characteristics were also extremely similar to that of Chifuyu, it's safe to assume that she had decided to fall in love with him right then and there. As time progressed, her feelings for him deepened to the point she started acting like a typical girl in love. Even becoming very shy from happiness when Ichika hold her or compliment her looks.
- Maya Yamada - His assistant homeroom teacher in Class One and a former IS Representative Candidate of Japan. They have a mutual respect between each other. Even if Ichika accidentally groped Maya's breast during an IS demonstration, the latter didn't seem to be too much bothered about it (though she started daydreaming about the possibility of being Chifuyu's sister-in-law). The two would often find themself in similar situations when their training due Ichika being in positions where he ends up noticing her large bust through her IS suit.
Students (including classmates from other years)Edit
- Honne Nohotoke - The two seem get along with each other even before Ichika was forced into the Student Counil. Ichika even recognizance her more out of all the other girls in the school outside of the girls he's usually with.
- Tatenashi Sarashiki - The Student Council President in the IS Academy and the IS Representative of Russia. She is his bodyguard, his third roommate and often creates mischief for him. He usually doesn't like her company because she always ends of teasing him. But when it comes to important matter (such as Phantom Task or family), they would talk to each other more seriously. Although she would usually break the atmosphere by teasing him or playing a prank. She appears in Volume 5 and Season 2 episode 1..
- While she doesn't mind teasing him or putting him in situation he doesn't want to be, she has compete trust in him. She even asked him to partner with her little sister when she was having trouble getting along with her. This ended up leading the two sister to finally make up with each other. Afterwards, she question herself why she asked him in the first place and admitted to herself she wanted to flirt with him, blushing as result.
- In Volume 8, after Ichika saved Tatenashi from being being kidnapped by the American special forces, she reveals her true name, Katana, to him while they were in the Academy's infirmary. She also exhibited a jealous reaction towards Ichika after mentioning the lewd exploits of the fake Ichika's and the other girls. This suggest that she does feel the same way the main harem does since she asked him to do similar things to her as well (even the manner in which she asked him do it was also different from the ways she used to do it before; in a shy, nervous tone compare to her previous playful, straightforward one).
- Kanzashi Sarashiki - Tatenashi's younger sister. The IS Representative Candidate of Japan and Class Four. He asked her to be his partner during the tournament at the IS Academy (Tatenashi asked him to do it). Since people usually are not nice to her, she took it as a bad joke and slapped him. After that event, she started to fall for him, so she finally accepted his petition. She appears in Volume 7.
- Her feelings for him seem to be connect to love for heroes. As such, she view Ichika as her hero (someone who will always be there for her and protect her). At the end of Volume 7 and episode 9, she confess to him. But because they were talking about anime, she believe (which is most likely true) that Ichika thought she meant anime and not him.
- She behaves like the other girls who love him do. Shy when he compliment her looks but will become angry with him when he compliment another girl. Although, compare to the other girls who would use their IS or a real weapon on him, kanzashi hasn't yet (but doesn't hide the fact that she anger with him).
- Natasha Fairs - The IS Representative Candidate of USA and the pilot of the Silver Gospel. She appears in the end of Volume 3 (does not appear in the anime) when she walks into the bus (taking the IS Academy students back from their field trip) to look for Ichika. She is grateful for him having saved her from the control of the unit, and kissed him on the cheek as her way of thanking him, unknowingly getting him into trouble with the girls. After kissing Ichika on the cheek, she left the bus and talked to Chifuyu only to blush when the latter complained about her kiss that created unnecessary sparks.
Civilians from outsideEdit
- Chelsea Blackett - Cecilia's maid and childhood friend. He first meets her in Volume 4 with Cecilia as his companion. The latter begins to suspect the rumour that 'Ichika likes older women' based on the former's interactions with Chelsea. Unknowingly this results in Cecilia pounding on the possibility of becoming an older women to attract Ichika's attention.