|Water Stream Rock Smashing Fist|
Sour Face (Formerly)
|Manga Debut||Chapter 21|
|Anime Debut||Episode 7|
Water Stream Rock Smashing Fist (流水岩砕拳, Ryūsui Gansai-ken) is a martial art.
It has been shown to be extremely powerful when used by a skilled fighter. Charanko describes the martial art as "leading enemies around the nose by moving like a calm stream, only to finish them off with a punch strong enough to smash great rocks like a raging river", implying that the Water Stream Rock Smashing Fist parallels real-life Tai Chi. The martial art can repel the attacks of his opponents, nullify them, or redirect them with twice the power. Furthermore, if in a crisis, the martial art has the user's body move on its own.
- Water Stream Encampment (流水陣, Ryūsui-jin): Performed by Bang. Bang is able to create an area where his fists will destroy anything that enters, protecting those inside. First used to protect Genos from the falling meteor debris.
- Instantaneous Effect (瞬身功, Shun mi Kō): Performed by Bang. Bang jumps at his opponent using a special stepwork, he elegantly quickly moves as if he was flowing, and confuses them with a swift feint and then performs a fast piercing attack, strong enough to create a hole in the body of a Fuhrer Ugly, a Dragon-level Mysterious Being. First used against Melzalgald. He precisely aims for the enemy's weak points from places they cannot predict.
- Fang Interpolation (牙挿指, Kiba Sōshi): Performed by Bang. Using the fingertips that he has trained, he can hit the smallest weak points with single hits of incredible accuracy. This move is known to be smooth like water but powerful enough to destroy rock with unparalleled destructive power.
- Abandonment (見切り, Mikiri): Performed by Bang.