I have a copy of Ikuzo's Merc Force....
Overall, pretty bad...
Yet, you can still get this vibe that the cast & crew are doing it for fun, & are having fun doing it, which, for me at least, makes it watchable...
I got the same vibe from watching
Horror of the Hungry Humongous Hungan (1991). Obviously filmed in the mid 1980s in rural county USA (lots of young guys sporting authentic mullets), it appears to be a friends & family project. It is quite awful but they still had fun doing it. Too bad Troma got a hold of it, re-edited and changing the title.