About a dog exposing himself.

A group of 3 yakuza failed their boss for the last time. After messing up an important job, the boss gives them 2 choices: Honorably committing suicide, or go to Thailand to get a sex reassignment surgery in order to becomes "female" idols. After a gruesome year long training to become idols, they successfully debut, with overwhelming popularity, much to their dismay. This is where their tragedy truly begins.

The "love, revenge, and feel-good" story centers on a young man who swears revenge against the yakuza. He studies the art of the "assassination fist" with all his might, and becomes an adult. But this man who is a genius at his martial art form realizes his techniques cannot actually be used to kill anyone.

(Source: MangaUpdates)