Orange throwing stars

Does anyone know where I can recharge these stars? I tried pretty much everywhere.. even the new ninja castle where they used to sell them but nothing.
They dont even show on my use tab when i enter the npc as in like they were "untradeable-one of a kind"

have you tried showa?

have you tried showa?

Yeah that was the first place I went when I noticed I couldn't recharge in the places where I should be able too.

I saw a video from years ago of somebody recharging them with Shinta in Showa. Don't know if that still works.

Used to be Showa, not sure now