Rinne (16) tries desperately to not touch his adorable little brother (11). He wants to make Hiiro feel good. Do you think Rinne would crack under his desires first or Hiiro's burgeoning sexuality going into adolescence would drive him to make the first move? Maybe Hiiro does something that gives Rinne a little a push towards acting on his urges. For example he masturbates while Rinne is "asleep" next to him or he gets hard while they are playfully sparring. Rinne being a good onii-chan will help him! There's definitely no underlying motives like years of wanting to touch little Hiiro's shota dick and see him all flushed and whimpering "Nii-san" and showing him how good it feels to cum by another person's hand.