Sun-Ken Rock is a japanese manga by korean mangaka Boichi.
The manga is based on Ken Kitano, the main character, who arrives in korea from japan after seeing that his high school crush, yumin, has become a cop in korea. Ken wants to become a respected cop so he can admit his love for Yumin again. But t doesnt happen and he lives his first year in korea as a shut-in. But after he beats up a few thugs that were shaking down a cart owner, he becomes the leader of a local gang. Ken finds himself getting deeper into the criminal underworld and not any closer to being able to confess to yumin!