Akiba, Moe, Imouto

Main character is a nerd. He sits at the computer or hangs around Akihabara all days long and seriously can't understand his sister who diligently attends the college. Childhood friend invites him to the university Akiba Circle where members share passion for Akihabara and sisters. This actually may be more fun that sitting at the PC.

[From vndbreview]