Tatsuzo was a Gunpla fighter during the 4th Gunpla Battle World Championship, when he was known as "Blazing Tatsu". Afterwards, he fell out of competition and began working as a land shark, extorting people to sell him their land through underhanded means.
When he threatened the inn that Misaki and her mother owned, he was challenged by Sei Iori, Reiji, and Mao Yasaka to settle the matter in a Gunpla Battle. He fielded a customized Apsalus III, which exploited Plavsky Particles to replicate the effects of an I-field. His machine was also capable of launching plasma leaders similar to those of the MAX-03 Adzam, and spreading the associated conductive powder. Ultimately, his Apsalus III was destroyed when Mao used his own Plavsky-bending skills to break out of the plasma leaders and charge up the satellite system of his GX-9999 Gundam X Maoh, damaging the Apsalus enough to let Sei and Reiji's RX-178B Build Gundam Mk-II finish it off.
In the wake of the defeat, Mr. Ral used his influence to ensure that Tatsuzo kept his end of the agreement, forcing him to leave the inn alone.
After the World Tournament was done, Tatsuzo was last seen helping out Misaki in the inn to repay his debt to her.
- Tatsuzo's burly stature, brutal temperment, and usage of an overpowering mobile armor bear a resemblance to Dozle Zabi of Mobile Suit Gundam.