from I Can See the Number of Times People Orgasm
Kotaha is Otoha's twin sister. Her sister and her often use the fact that they are twins to take tests instead of the other and get higher grades.

I Can See the Number of Times People Orgasm
A loser somehow gets the ability to see how much someone has reached orgasm from a voluptuous succubus. How will he use this power? Will this ordinary guy somehow be able to turn his love life around?