Masato Mishima is the aide of ZECT HQ's leader, Riku Kagami. He is also one of TheBee Zecter users. He also used the form of Gryllus Worm in episode 48 of Kamen Rider Kabuto. He is the final antagonist in Kamen Rider Kabuto.
He communicates several times with Sou Yaguruma and Shuichi Tadokoro to brief the ZECT teams about the Worms. Eventually, he was upset with Yaguruma botching a mission and Tadokoro questioning him about ZECT's agenda. There's implication that he has no faith in Kageyama as TheBee, despite Kageyama being loyal to ZECT and is looked down upon by Kamishiro. He has no sense of taste, and finishes eating by taking a supplement. He forcefully became TheBee at one time despite the TheBee Zecter's attempt to reject him. He truly thinks Kageyama is an eyesore because he can only complain and has lost the TheBee Zecter. He also seems to have a connection to Rena Mamiya/Uca Worm and had always kept the Hyper Zecter with him. Renge manages to steal the case with the Hyper Zecter, but Uca Worm takes it back only to find that the case has been rigged with a bomb.
Mishima tries to destroy the Hyper Zecter with the bomb. After the explosion, he taunts Tendou for failing to obtain the Hyper Zecter. However, he doesn't realize the power of the Zecter as it manages to finds its way to Tendou, much to his chagrin. He then tosses his glasses to the ground in anger. He gradually loses respect for Riku Kagami's servile manner toward the Natives. After realizing Negishi found out about the Red-Shoes system, he makes a pact with Negishi and overthrows Riku Kagami as leader of ZECT. Using the Natives' pendants, he gains the ability to turn into Gryllus Worm, the strongest Native. He is defeated by Hyper Kabuto's and Gatack's Rider Kick and then destroyed by the meteorite explosion that obliterated the studio set.
OOO, Den-O, All Riders: Let's Go Kamen Riders
Kamen Rider TheBee was part of a group of reinforcement riders led by Akira Date/Kamen Rider Birth to aid the primary riders in defeating the Rock Great Leader. All the Kamen Riders got on their bikes and performed the All Rider Break attack which destroyed the Great Leader. OOO, Den-O, All Riders: Let's Go Kamen Riders Although there is no information on TheBee's human form, this incarnation of TheBee could be Mishima, as he somehow appears to have been revived by unknown means.
Kamen Rider × Super Sentai: Super Hero Taisen
In Kamen Rider × Super Sentai: Super Hero Taisen, Gryllus Worm is one of Dai-Shocker's Great Commanders. He takes on the Gokaiger successfully, but is later seemingly defeated by the combined Rider and Super Sentai forces. In the background of both aerial attack scenes, he is first seen fighting NinjaYellow, then ShinkenRed and DekaBlue. His human identity isn't made clear in the movie.
Kamen Rider Wizard
Gryllus Worm was one of Amadum's monsters in the world within the Magic Stone.
He only used the TheBee Zecter only for short period. In the episode of 48 of Kamen Rider Kabuto, he assume the form of the strongest Native Worm, Gryllus Worm.