Weretiger is a Phantom born from a man called Igawa when he gave up in despair. Igawa described himself as a "muscular man", who seems to be focused on strength training but is even strongest in his true form.
Weretiger is ordered by Medusa to go after the Gate Toshie Nitoh, Kosuke Nitoh's no-nonsense grandmother who came to Tokyo to take Kosuke back to their home in the Fukui Prefecture.
With aid from Gremlin, posing as a bus driver, Weretiger reveals Kosuke's identity as Kamen Rider Beast to Toshie as she willingly offers herself as a sacrifice to nourish her grandson.
Just as the trade with the captured Shunpei for Toshie take place so that Weretiger can put Toshie into despair by killing her grandson, Haruto intervenes and he and Kosuke fight Weretiger and Gremlin, with the latter getting his Beast Driver back.
After Kamen Rider Wizard handles with Weretiger via the use of the Drago Timer, he lets Kamen Rider Beast finish him off with his Kick Strike.
- Gate: Igawa
- Episodes: 24-25
- Destroyed by: Kamen Rider Beast's Kick Strike
- Mythological Basis: The Weretiger
- Height: 241 cm
- Weight: 170 kg