Azito [Major Wave Series] Japan

In Azito, the protagonist builds and manages a secret underground facility which develops secret weapons, monsters worthy of Godzilla screenings and war machines. Supported by an army of scientists, the secret installation sits on the cutting edge of exotic military research but to support the massive industrial complex, commercial items for the masses must also be developed and sold for revenue and profit. The secret base is independent of governments, thus the need for self-sufficiency and profitable products to peddle.