| 志熊 理科|
|School||St. Chronica's Academy|
|Japanese Voice||Misato Fukuen|
|English Voice||Alexis Tipton|
|Novel Debut||Rika Shiguma|
|Manga Debut||Chapter 13|
|Anime Debut|| Episode 1 (Cameo)|
Episode 4 (Official Debut)
Rika Shiguma (志熊 理科, Shiguma Rika) is a main supporting character from the Boku wa Tomodachi ga Sukunai series, a freshman and scientific genius whose presence at St. Chronica's Academy was designed to increase its prestige. She was saved by Kodaka when she fell unconscious during a disastrous lab experiment (she invented and released sleeping gas that works in just a few seconds), and begs to repay his kindness with sex. She joined the Neighbor's Club just to get closer to him.
She is the fifth member of the club. Rika was a shut-in before joining, being isolated from the outside world her personal room in the school, she prefers the life of a loner like Yozora and like her, is extremely anti-social.
Rika has dark eyes (light-brown in Season 2) and hair. And as described by Kodaka, Rika has a slightly childish and, at their first encounter, beautiful face (to which Kodaka would say it's a waste due to her perverseness).
In the first three volumes of the light novel, Rika is usually depicted wearing her glasses, with her hair in a ponytail being held by a yellow scrunchie. By the beginning of Volume 4, she stopped wearing her glasses (which she said to be fake, since her vision is perfect) and began to let her hair flow down to her back, still being held by a scrunchie. She soon started changing her hairstyles frequently. She also changed her hair color to blonde and black in Volume 5 (using her new invention), but she quickly got back to her natural hair color in Volume 6. In Volume 8, she changed her hair color back to black during her second confrontation with Kodaka at the rooftop.
However, Rika's dress code tends to be the same, consisting of the normal school uniform with a lab coat over it even in public. Rika once changed her clothes to a one-piece dress in volume 6 after Kodaka commented (in one of his "accidental" asides) that she would be a real beauty if she dressed up. In Volume 8, Rika began to wear more casual clothes inside the club-room.
Rika also owns a yellow bikini but she still wears her lab coat over it.
Although there are many adult themes in the series, Rika is considered to be the most sexually straight-forward member of the neighbor's club. This was clearly highlighted in her first appearance, when she described her attraction to rape Kodaka in the middle of a stunned class. She has a habit of inserting any sexual innuendo possible in her sentences, to the point where she finds it normal to convert any innocent thought into something perverted.
True to her word, Rika is an avid (self-proclaimed) fujoshi: she is a passionate consumer of Yaoi manga and magazines, is comically aroused by intercourse between mecha, and is delighted when Yukimura offers to have sex with Kodaka. Rika is proud of her perverseness, as she says that she would be a boring person if people only thought of her as a genius girl. She also greatly enjoys BL-related media, mostly H-games and novels, to the point of watching one in front of everyone and fantasizing about Kodaka with Yukimura (before Yukimura was revealed to be female).
Despite her perverseness, Rika is shown to be very caring towards her club-mates as she is very sensitive to everyone's well-being and is almost always depicted in high-spirits. She is quite pestered by the fact that her club-mates usually feign ignorance about their already-established friendship by claiming that they are still friendless and view each other only as club-mates, especially Kodaka.
Rika seems to delight in shocking others with her forwardness, especially the unflappable Kodaka. His casual manner of dismissing her advances becomes a major source of frustration for her, however. Throughout the series, he responds increasingly cooly to Rika's attempts to get his attention, to which she is visibly disappointed.
While Rika enjoys shocking others she is easily overwhelmed when any sort of genuine affection is leveled at her, and usually blushes intensely when receiving it. Kodaka surprises her on at least two occasions by "accidentally" speaking aloud while he is meditating on how attracted he is to her, and Yozora's inclusion of her during the Culture Festival elicited a similar reaction.
Despite her sporadic persona, Rika is perhaps the most dedicated member in terms of achieving the club’s intended goal to make friends. Unbeknownst to the other characters, except for Kodaka, she puts forth a tremendous amount of effort behind the scenes to make some club activities, such as the VR game and club film, an enjoyable experience for everyone.
Rika also likes to speak in third person format to further show her eccentricity.
In the light novel, it was indicated that Rika may be masochistic.
- Mad Scientist (Self-proclaimed)
- Fujoshi (Self-proclaimed)
- Bullseye Rika (Self-proclaimed) 
Rika is considered to be a genius, and is possibly the most intelligent character in the series yet, as she is smart enough to invent gadgets and things because of which many companies hire her for service. Even the school principal, Tenma Kashiwazaki came and invited her personally just to increase St.Chronica's prestige. However, in terms of Japanese language, Rika tends to write her sexual thoughts in too, causing much trouble.
Rika is also extremely observant as she is able to identify the minute details of Kodaka and Yozora's behaviors towards each other and was, thus, the only one who suspected that Kodaka and Yozora were friends before the latter told the rest the truth. Rika was the first to realize Kodaka and Kobato’s source of social predicament, as well as to realize the fact that all the members of the club are already friends, thus accomplishing the club’s original objective. Because of this skill, Rika was (ironically) the only one who understands what Kodaka really wants and desires.
In terms of stamina, Rika is rather weak as she cannot handle running around the school for three times (while Sena did it effortlessly) and becoming extremely fatigued after standing for a long period of time. Just like Yozora, she cannot stand crowds.
- Rika's surname, Shiguma (志熊) literally means "Bear Journal".
- According to the chapter footnotes regarding Rika Shiguma's name, "Shiguma" 志熊 translates to the greek letter "Sigma" and Rika, while being a typical girl's name when romanized, has a kanji 理科 that translates to "science".
- Rika apparently has acrophobia, as she would "snap" and insult in vulgarities on gravity and Newton when going to high places.
- Rika said that she has kissed a jellyfish, planarians, and even arthropods, but does mention that she wanted her first mammal kiss to be with Kodaka.
- Despite wearing glasses, Rika claims that her vision is perfect and her glasses are only meant for fashion.
- Like Sena, Rika is also an avid gamer. Specifically galge, eroge, BL games, otomege and the like, but not as much devoted as Sena.
- As of Volume 8, Rika decides to "officially" become Kodaka's friend and thus, Kodaka became the first friend she's ever had.
- Rika has the largest set of varying appearances in the series, mostly referring to her number of hairstyles.
- "F*ck, f*ck, f*ck, f*ckkkkkkkkk! God damn gravity you piece of sh*t...! You don't care who it is as long as you can pull down on them, do you, you little b*tch!! Gravity, you piggy b*tch sl*t! Holy f*cking sh*t what a god damn whore you are...! Hah, you're Earth's greedy little sl*t, you damn b*tch in heat! F*ck you universal gravitation, you're just Newtonian Mechanics' dirty little whore! You're just the crusty semen left over in that sl*tty apple's p*ssy after that son of a b*tch Isaac f*cked its rotten juices! Special theory of relativity, you impotent phimosis piece of sh*t! Einstein, you old limp d*ck f*ck! What, got something to say!? Then move that tiny little twig of yours faster! C*m faster than the speed of light! A pig that can't fly through space-time is just a piece of sh*t that reeks of semen and can't even last 5 seconds in his wet dreams! F*cking f*cking f*cking f*cking f*cking f*cking f*cking UNIVERRRRRRRRRSSSEE!!" (in Volume 5, during the Black Dragon ride)
- "Always gets lonely, but is scared of having others show they honestly care. Pretends not to notice. Pretends not to hear. Run away. Brushes it off. Avoids the issue. Refuses. Even turns to self-deception, spinning lies such as 'There's no way anybody likes me.' " (confronting Kodaka in Volume 7)
- "I told you this would happen." (Rika, referring to Kodaka, after Sena's confession in Volume 8)
- "Eh? What'd you say?" (Rika's answer to Kodaka's confession of asking her to be his friend)
- "I mean, aren't we all friends already?" (Rika infers to Kodaka the obvious truth about the Neighbor's Club)
- “Let’s go in the back and make babies!” (Rika makes this comment after Kodaka says he wouldn’t mind seeing her wearing something more revealing on the train)