The TennoKoe Bank is a memory backup device made by Hudson in 1991 for the PC Engine range of games consoles from NEC.
There is no modern equivalent.
It's powered by an internal battery and was not designed to be user serviceable.
Given that these devices are now over 25 years old, they are starting to fail as their internal batteries die.
I made this site to give people the option of getting a TennoKoe Bank that they don't have to worry about for a long time.
Adhesive gasket replaced
New outer jewel case
Your existing save data can be retained during refurbishment.
With care, refurbished cards should last another 20+ years.