From Vices and Devices:

Isayama Natsu is a free spirit: he doesn't wear socks, he sets butterflies free from rooftops, and he gives blow jobs to other boys in the school tool shed. And Taneda Kouki, who believes himself normal in every possible way, accidentally sees the last one while taking a shortcut. Isayama bewilders and fascinates Taneda, who also begins questioning his own normality...