Replying...
Intro. Yui was normally in a shed with a female for about 4 hours a day, being one of the only 3 males in the whole village. Meanwhile, Akira, the more underdeveloped twin, was left outside, and his manhood unharmed. He is starting to become more developed, however, and keeps the secret to himself and his brother, not wanting to get the treatment Yui gets. The twins are 13 and turned 13 recently.

Yui & Akira

@Matthew