Ryukotsuki appears as the main boss in Harmony of Despair's DLC chapter, The Legend of Fuma. He transforms into three different forms:
- In his first form, he's just a regular-sized cloaked enemy wearing a horned skull mask. He attacks by shooting fireballs and jumping at the heroes from time to time.
- His second form is a tall warrior with long red hair and heavy armor. He wields a shield and attacks by throwing knives at the heroes.
- In his third and final form, he'll transform into a gigantic dragon-like demon conformed by different kinds of bones, with his arms and legs being made by several skulls. A red orb is encased inside his thoracic cage and serves as the monster's weak spot, although it's impervious to most forms of attack. He attacks by summoning a series of swords to rain on the heroes, by swiping with his claws, by shooting three bouncing fireballs from his mouth, and by summoning an alien-like creature with two heads. His humongous size can also be considered as a form of attack, as he'll advance toward the heroes, reducing their area to maneuver.
|Enemy Data: Ryukotsuki|
|Image||Name - Game|
|A fiend who hails from the deepest pits of hell.|| Drop: Yasutsuna +1 (Hard), Muramasa (Normal), Muramasa +1 (Hard), Nebula (Hard), Luminatio (Both difficulties), Healing Mail (Normal), Fuma's Greaves (Hard), Ebisu Raiment (Normal), Thief Ring (Normal)|
Soul: Ryukotsuki (0.5%)
| Chapter 11|
- Ryukotsuki also appeared as a card in Yu-Gi-Oh!, along with Getsu Fuma, the protagonist of the game Getsu Fūma Den.
- A female parody of Ryukotsuki appeared in the 2011 Xbox 360 horizontal scrolling shooter game Otomedius Excellent, along with Gesshi Hanafuuma, a female parody of Getsu Fuma.