Rika Seo (妹尾 梨可, Seo Rika?) is a first-year student at Kazemai High School and a member of the kyudo club. She is the captain of the girls' team.
Rika is a tall girl with short, straight dark brown hair and dark, narrow eyes. This appearance, combined with her stoic personality, creates a certain tomboy-ish charm and cold "cooleness", which is why Yuuna even proudly tells Nanao that "Seo is cuter than any of our guys" to stop his self-loving flirting behavior.
As the captain of the girl's club and the most experienced female member of the club, Rika turns out to be widely respected or even admired by other girls and her friends. Despite this, she is a rather quiet and calm person who speaks only when she considers it necessary.
All this makes Seo a tomboy-ish girl who, under certain conditions, can even be confused with a boy. It seems that Rika herself completely ignores this, but this several times becomes the cause of clashes between girls and the womanizer Nanao, who likes to poke fun at her boyish features.
In this regard, of the three girls, she contrasts most strongly with the emotional and clumsyly communicative Röhei of the three main guys, with whom Seo also shares tall stature and "connecting" function.
Rika went to the same middle school as Noa Shiragiku. As their school did not have a kyudo club, they practiced at a local kyudojo.  In high school, she and Noa quickly befriended Yuuna Hanazawa and they all joined the kyudo club.
Kyudo Club Practice Edit
Rika is one of the members summoned by Tomio Morioka, who tells them that he wants to participate in the Prefectural Tournament. Rika is too caught off guard to respond, so Yuuna Hanazawa and Noa Shiragiku, the other two girls summoned, answer for her. Yuuna asks Tomio if they will be good enough for the tournament by then, as it is in the middle of May. Noa says that even though she has experience, she has never been in a competition before. Nanao interjects that they should do it and that he will be motivated if he is with a cute girl. Noa coldly tells him to be quiet and to be considerate of Rika's feelings, causing him to fall silent. Tomio tells that he thinks that they all shoot well and that they could participate in individual competitions, as they are not enough people for team competitions. The three girls confer, then Rika relays their agreement. 
- Yuuna Hanazawa and Noa Shiragiku - Seo is widely respected by the remaining members of the girl's club, especially Yuuna, who admires her and considers her a very cute girl and talented archer. To some extent, their trinity is even contrasted with the trinity of the main guys, where Rika corresponds to Seya's calm reasonableness and the unifying function of Ryouhei.
- Nanao Kisaragi - Rika and Nanao can be fully called complete opposites and the plot seems to like to emphasize this slightly. However, at the moment it happens completely one-sidedly, as Seo ignores any of his banter, and instead Nanao is jokingly arguing with Noa and Yuuna, who protecting her.