The secret between school clerk uncle and little twin sisters

The secret between school clerk uncle and little twin sisters.

A hairy fat uncle.
Working as a school clerk of the school for 15 years, he still has no experience of relationships at the age of 40. He often peeks at school girls wearing swimsuits or gym wears under a pretext of cleaning works.

Mana (who wears pink hair ornaments)
Older twin sister. With her preceding grades and courtesy, she is popular among teachers and boys. Although she is in a early adolescent age, she has more interests on adult men than boys. One day in break time, Mana noticed the clerk uncle and talked with him. Since that day, Mana can't take off her eyes off the clerk uncle.

Nana (who wears green hair ornaments)
Young twin sister. She has better performance in Physical Education, but doesn't be taken much notice by others. Nana is often compared with her older twin sister by others. As a result, Nana became a more retiring, less confident girl. The clerk uncle seemed to like it way and approached to Nana, useing her self-abased complex to get the further relationship...