Tenshi-san wa Aragaenai: Do S na Douki no Amai Meirei

"Why am I doing this with Masho...?!" Amatsuka and Masho work in the same company together and have been around each other since elementary school. Amatsuka has always viewed Masho as a rival but has never been able to win at anything against him, and at the same time learned that she has a rare condition called "Dynamics" divided people into "Doms" and "Subs"... but she's a sub! And she's quick to find out Masho is a Dom! Source: MU