Muramasa showed up in "Wired for Battle!" (Episode 142) as a character of the day.
He's a former elite Pokémon Trainer who got tired of the winning streak and switched gears to open an elite training school positioned between Cherrygrove City and Azalea Town. His reputation draws serious students from all over the world.
The whole episode basically centers on his son Shingo, one of his top students, who became way too confident after developing this laptop program he believed could predict any battle outcome. Muramasa figured the kid needed a reality check, so he went looking through the nearby forest for someone strong enough to prove Shingo wrong. That's when he spotted Ash and Pikachu and invited them to the school. His instinct paid off—Ash's Heracross ended up beating Shingo's Scizor, which was a major wake-up call for the kid. After the loss, Shingo actually thanked Ash for the match and committed to training harder under his father.
Content compiled by AnimeList.moe from publicly available sources.
