Satoshi Tainaka

Satoshi is Ritsu's younger brother. He appears when Ritsu is walking home with him from the movies. He then ventures of with a friend from school he saw on the way home. He seems to respect his sister Ritsu but still acts like a normal boy.
Satoshi seems to be a bit more mature than Ritsu, usually saying things like "Geez, be more careful next time" when he has to take care of the problems she caused. Satoshi knows Mio because she and Ritsu have been friends for so long, but becomes shy when Ritsu brings the rest of the Light Music Club home without telling him (Ritsu supposed it as a "rebellious phase"). He is also curious about his sister's doing and eavesdrops sometimes at her door (for example, when Mio and Ritsu were practicing for their class play, Ritsu finds out that Satoshi is laughing outside her room as she practices her dialogue). He also dislikes cold weather. Although he sometimes laughs about his sister or tells her to be quiet when she practices in her room, he still respects her and asks her for permission to hang out with his friends.