Raika Oda is a second-year Literature student at Tama University and the sole female member of the Street Observation Research Society. Within the club, she shares close friendships, especially with Yuuta Segawa. She acts much more openly around Yuuta than her typically reserved self does with others.

She possesses long, wavy purple hair with face-framing bangs, red eyes, and average height. Her prominent bust and frequent choice of cleavage-revealing outfits draw significant male attention on campus. Emotionally restrained, she rarely voices her feelings and generally keeps conversations brief, though she readily engages with Yuuta and occasionally teases him. A defining trait is her intense fondness for cute things, particularly young children like Hina Takanashi. Such encounters trigger unusual squeaks of delight, dramatically shifting her usual composure.

Raika excels at Japanese cooking and is recognized as a skilled cook. She actively assists Yuuta’s family by preparing meals and sharing culinary knowledge, like teaching Sora Takanashi techniques to improve her abilities. Raika employs physical discipline within the club, wielding a harisen to strike Shuntarou Sako when he makes inappropriate comments, such as calling Sora a "grandma".

Her character evolves through sustained interaction with Yuuta and his nieces. Initially detached, she gradually integrates into their familial life, offering practical support like childcare and household management. This fosters a subtle maternal role, particularly with Sora, who unconsciously views her as a mother figure despite initial jealousy over Raika’s closeness to Yuuta. Her community engagement deepens through participation in neighborhood activities, often facilitated by the girls' presence, expanding her relationships beyond the university circle as the family integrates into broader social networks.