Knew I'd seen this somewhere (Recognized Hirano's style and the tone of the dialogue). This is direct parody of the final page of 'Drifters' (Hirano Kouta) volume 2 chapter 6 (chapter 17 overall). It parodies, the style, panelling, speak bubbles and dialogue. Everything, even the placement of 'TO BE CONTINUED' (Technically even the context is similar, although much less dark).
Everyone in this mahjong house is shit.I'll kill everyone in this mahjong house.It's a bloodbath.It's an extermination.I was mistaken.