iirc there is no "fan" scroll in the sengoku shop, so there is no reason to think that there would be a katana scroll. There are already 2h weapon scrolls in the sengoku shop, which is what we will be scrolling katanas with. or you could go for 20% scrolls, or 50% ones. just make sure to use 2h weapon scrolls, not 2h sword.
I say just save the coins to buy a reverse katana from the sengoku shop and use the epic potential scroll from the hot time on it and just deal with a clean weapon.
At least that's what I'm going to do.
Hayato's class-specific katana weapon is classified as a two-handed weapon. Note I said weapon, not sword.
You can use two-handed [i]weapon[/i] scrolls on it, which are sold in the Sengoku shop.
You simply cannot use two-handed [i]sword[/i] scrolls on it, because that's completely different and specific to two-handed swords in the game.