"You let Anti make a kaiju? Why?"
"Because Anti despises Gridman much more than you do."
"The stronger the hatred, the stronger a Kaiju is born- *screen gets kicked*"
- ―Akane questioning Alexis on the mysterious UFO, Scheme
Subtitle: Gloomy Grudge Monster (幽愁暗恨怪獣 Yūshū Ankon Kaijū)
Eager to fight Gridman, Anti chased Yuta Hibiki down at school, demanding he fight as Gridman. However, he was told that Gridman would come only if there was a Kaiju around. Anti then left and along the way, he got the idea of sneaking into Akane's room and asking Alexis・Kerib to create a Kaiju for him. Alexis accepted the request, saying that Anti's hatred towards Gridman would make a great monster. Shortly after, a lance-like UFO appeared in the sky. Gridman appeared and destroyed the UFO after a short fight but it was able to regenerate itself, giving him some trouble. Combining with Sky Vitter, Sky Gridman flew upwards and found the real body controlling the UFO like a marionette. Anti was standing on its head and transformed. After a brief aerial chase, Diriver was destroyed by Gridman using the Gridknight Saber Slash.
Diriver, along with all the other Kaiju Gridman fought, reappeared when they were summoned by Alexis to get rid of Gridknight, since Akane refused to make any more new kaiju. Diriver was cut in half by Gridknight, who used the Gridknight Calibur to perform the Knight Calibur End on Diriver.
- Designer: Ichiro Itano
- Its counterpart in Gridman the Hyper Agent is Stealgun, a monster who is known for aerial superiority.
- It resembles the monster Tsuifon from the Ultraman: Super Fighter Legend OVA. Helps that Ultraman Hikari also made a cameo appearance in that anime, wearing the OVA-style battle armor, like his cameo in the episode this monster appeared in.
- Since Diriver is not a creation of Akane, its design is made differently from normal monsters as a "monster made by a monster" in the anime and its roar is processed by Kenichi Suzumura instead of Reina Ueda.
- Height: 70 m
- Weight: 42,000 t
- Powers and Weapons
- Flight: Diriver is able to fly.
- Diriver UFO (ヂリバーUFO Djiribā UFO): Diriver uses a lance-styled UFO to attack with, controlling it from high above using long strings, to avoid detection. It is 42 m tall and weighs 70 tons.
- Regeneration: The weapon regenerates itself within a few seconds after destruction.
- Claws: When forced into direct combat, Diriver attacks with its sharp claws on its hands and feet. However, it is not very proficient at using them.