-
You can source the standard black Prospex silicone strap that they fit to the turtle, etc. The steel keeper and buckle are maybe a bit shiny for the style though.
Edit: actually the “ninja turtle” ( https://www.seikowatches.com/global-en/products/prospex/SRPC49K1 ) has a black buckle and keeper version. Wonder if you could find the part number and order it. Bet it would be prohibitively expensive though.
Such a dope watch, if the date was at 3 rather than 4 I probably would have bought one. Still a big fan.