This post is for informational purposes only, please review the manufacturer documentation and specifications before using any replacement parts in your application.
2SK2605 is an N-channel MOSFET from Toshiba that appears to have been discontinued for some time now. Based on the information I found in an upload of the old datasheet, DigiKey part number TK6A80ES4X-ND should be a good alternative for it. This alternate is also manufactured by Toshiba.
The main difference seems to be that the replacement part has a slightly higher rating for continuous drain current (6A vs the original part’s 5A), but I still recommend looking over the datasheet to verify that this will work for you.