Small Chisel, Triangle, Carving Chisel, Chipped, Carpenter's Tool, Carving

I believe this is a chisel by Koshin. I don't know the specifics. Please judge from the image of the maker's mark.
It was used by my father. He also had other chisels by Koshin.
There is a large chip. When I asked a professional sharpening service for an estimate, they said it could be repaired for about 4000 yen. I can introduce you to a sharpening service.

- Type: Triangular chisel
- Handle material: Wood
- Overall length: Approx. 230mm
- Blade condition: Shows signs of use

Thank you for looking.