Protagonist Hikida Tooru is a withdrawal living at home in Tokyo. Schoolgirls younger sister such him, It despised it.

Protagonist that spends the moping life, A certain day, The Bible is bought by soliciting the religion that came by chance. The aphrodisiac of Obscene entertainments was kept secret in it why. Naturally, It practices it to a hateful younger sister. Then, isnt any she under elder brothers thumb?

Thus the prologue of shame to younger sisters "Milk drinking doll" started......