- Yo-kai Watch: Wibble Wobble: Playable Yo-kai (Shadowside form only)
- Yo-kai Watch 4: Befriending Yo-kai
- M04: Supporting Yo-kai
- Yo-kai Watch Shadowside anime series: Supporting Yo-kai
In his Lightside form, Seiryuu takes on a humanoid appearance, reminiscent of Whyvern King. He has long, dark blue hair, and two cream-colored, short antlers.
His body appears to be clad in a skin-tight black suit, or perhaps countless black scales, over which he wears light blue and green kimono-like clothing, as well as a multi-layered dark green belt with gold lining and fluffy fur stitches on the bottom of the belt as well as black sandals. He also wears a golden bracelet.
In his Shadowside form, Seiryuu has the appearance of a dragon, similar to how he appears in the present series. His hair is now a dark blue mane, and his antlers have grown bigger. His scales are light turquoise, and his underside is light blue. He has four limbs, and a crest of the same color as his horns on his chest.
Seiryuu is a supporting Yo-kai in Yo-kai Watch Shadowside: The Return of the Oni King.
Seiryuu is one of the Yo-kai summoned by Natsume with the Yo-kai Watch Elda to aid her in the fight against the Oni King Rasen. He also gives Natsume the Keystones for Fubuki-hime (Shadowside), Rai Oton (Shadowside), and Merameraion (Shadowside). They manage to trap him and then unleash a powerful attack. However, this only reverts him to his De-armoured form, which now possess far higher speed, and they are quickly finished off.
It's also revealed that it was he who saved Natsume from drowning when she was still a young child.
Yo-kai Watch: Wibble Wobble
- He is voiced by Ryōtarō Okiayu