Wanting nothing but a quiet life where noone will
bully her, Usa somehow finds herself adopted into Rin's group of misfit
friends. Quiet and shy, she often finds herself and her unusually large
breasts at the butt of the joke. Unlike Rin and Kuro, Usa is extremely
naive when it comes to sexual matters and has to rely on her friends
for advice - which is not always the best thing when she is completely
in love with Rin's cousin, Reiji.