"A monster with one eye and one leg, said to live deep in the mountains of Kumano, Japan. A single footprint measuring 30cm has been sighted in the mountain's snows"
—Shin Megami Tensei: Strange Journey compendium
Shin Megami Tensei IV
Ippon-Datara can be found in Shinjuku. He can teach Flynn the Fang Breaker, Tarukaja and Maragi skills through his Demon Whisper.
Ippon-Datara also appears as an opponent in the Challenge Quest, "Training Battle 1." In this battle, he will alternate between using the Heat Wave and Maragi skills. Flynn, Dzelarhons, and Pyro Jack will automatically repel its Maragi attacks. As it only lasts one turn, the Tetrakarn skill needs to be reserved for turns where Ippon-Datara uses Heat Wave, otherwise the party will be wiped out. Ippon-Datara will always use Heat Wave on the first battle turn. Additionally, Flynn's gun is equipped with poison rounds, which can inflict additional damage on Ippon-Datara is he becomes afflicted with Poison status.
Shin Megami Tensei IV Apocalypse
Ippon-Datara can be found within Kanda-no-yashiro. He can bestow the Power Punch, Mudo and Oni-Kagura skills through his Demon Whisper. He receives a decent bonus to any Physical skills learned.
Ippon-Datara later becomes the focus of a quest for the Hunter Association, called 'Flying Sparks, Rolling Water.' Tatara of the Artisans' Union puts out a request for a hunter to bring them an Ippon-Datara, so that it may provide them instructions on smelting techniques for creating weapons.
Devil Summoner: Soul Hackers
"A monster with one eye and one leg, said to live deep in the mountains of Kumano, Japan. A single footprint measuring 30cm, said to belong to Ippon-datara, was sighted in the mountain's snows."
—Devil Summoner: Soul Hackers 3DS compendium
Devil Summoner: Raidou Kuzunoha vs The Soulless Army
"A monster with one eye and one leg, said to live deep in the mountains of Kumano, Japan. A single footprint measuring 30 centimeters has been sighted in the mountain's snows."
—Devil Summoner Devil Chart
Devil Summoner 2: Raidou Kuzunoha vs. King Abaddon
An Ippon-Datara serving Dr. Victor is disguised as a maid, and gives Raidou Kuzunoha the XIV the doctor's first request. He shows up later to tell Raidou about his master's new branch of Sword Fusion, while complaining about the maid outfit.
"A one-eyed, one-legged monster said to live deep in the mountains of Kumano, Japan. Believed to be the degraded blacksmith god, Ame no Me-Hitotsu no Kami."
Ippon-Datara is one of the Personas that Margaret requests as part of increasing her Social Link and building the Empress Arcana. As her first request, to reach the 2nd rank in her Social Link, she ask to see an Ippon-Datara that has inherited the skill Sukukaja. It can be obtained by fusing either a level 10 Ghoul with a Yomotsu-Shikome, or by fusing a Sylph with either an Archangel, a Lilim or a Cu Sith.
"A one-eyed, one-legged monster said to live deep in the mountains of Kumano, Japan. It's believed to be the degraded blacksmith god, Ame no Me-Hitotsu no Kami."
—Persona 5 background
Ippon-Datara is a Persona of the Hermit Arcana and also appears as a Shadow with the title Embittered Blacksmith. He can be found in Madarame's Palace and in the Chemdah area of Mementos.
Yasuo Jochi's Shadow takes the form of Ippon-Datara during the request "Who's Muscling in Yongen-Jaya?" Shadow Jochi will use the Charge skill in addition to having his weakness changed to Electricity.