Rika is the daughter of two unnamed parents and grew up in an extremely accepting and tolerant household. This resulted in her having loads of personal freedom, which she used to experiment romantically, get involved in numerous protests, and get in constant trouble with law enforcement. Perhaps because of this wild behavior, Rika never had a good relationship with her mother, never having the time to patch things up before her death. At some point, she met a woman named Rie, who she'd go on to marry and, together, adopt a daughter.
Rika's backstory is part of a running joke in Lessons in Love. She often makes allusions to ridiculous or baffling tales, all of which she doesn't elaborate on. According to her, she's been in a cult, traveled the world with nothing but a shopping cart, been arrested for vandalism, and never even finished high school.
Rika bears a lot of similarities to her daughter, Rin. The two share the same off-beat but charming charisma, the same punk aesthetic, and the same emotional intensity. Unlike her daughter though, Rika is much more gullible and not nearly as intelligent, often finding herself as the butt of a joke when her ignorance is exposed — She makes up for this in her life experience.
While her general light-hearted demeanor would lead most to believe otherwise, Rika is among the oldest members of the cast, and has decades of wisdom she often shares when the moment calls for it. Additionally, while most write her off as empty-headed, she's very emotionally intelligent, easily picking up on people's social cues and harboring a surprising amount of hidden melancholy.
Rika names music as one of her strengths, something that was confirmed by Otoha, because according to her she can play pretty much every instrument.
Rika used to read often when she was a small child, and keeps a collection of various children's books she used to have. Despite this, she's not much a reader nowadays, preferring music.
Despite living together for many years, and raising a child together, Rika was never officially married to Rie. This is due to Japan's ban on homosexual marriage.