J⇔M

J is a professional hitman...he was orphan and raised by a syndicate as an assassin. He was too good, killed too many people, knew too much about the syndicate.
When the syndicate tried to erase him, they were backfired...when three syndicates were wiped out completely, J became "untouchable."

Megumi, a girl in third grade, was bullied by her classmates because she is half-Japanese, half-American and gets good grades. One day, when they bumped their heads...their bodies were switched. Now J is inside a cute girl's body...and Megumi is inside the tough guy's body.

Now they must hide that they are not who they were and keep their everyday life look the same as before.
J never knew how hard a girl's life is, and Megumi enjoys her new life!?

(Source: BookWalker)