Played on a RetroArch emulator. This is how to defeat Heishin 1st in Yu-Gi-Oh! Forbidden Memories in Campaign Mode on your first playthrough without taking any damage to your Life Points. It takes a LOT of farming and a LOT of luck, but it is possible with a deck that can easily fuse Summoned Skull and Twin-Headed Thunder Dragon and contains some equips for at least one of them. I went with SS equips because they're easier to obtain. For the farming rundown...
I got two Job-Change Mirrors from Villager 2 with S/A-POW wins (15/2048 chance), three Kunai With Chains from Jono with S-POW wins (33/2048 chance), one Sword of Dark Destruction from Teana with an S-POW win (16/2048 chance), and another one from Seto with a B-POW win (18/2048 chance). I also got enough star chips from the farming to buy Bright Castle, which costs a whopping 800 star chips, that's how long it took.