If you loved Mellow, try Gamera gegen Gaos - Frankensteins Kampf der Ungeheuer

What Gamera gegen Gaos - Frankensteins Kampf der Ungeheuer is

Lava-slick twilight, the first bat-winged shadow cleaves the thermal column. A shrike-like screech splits the sky as Gyaos begins its razor gust, travelers halved before flight bags land. An orphaned boy alone in a bunker feeds Gamera jelly sandwiches until the giant turtle trundles forth. Earth rumbles as the last creature who likes humans lumbers toward a daylight stand-off. A child’s lonely alliance against extinction, told in the shonky lexicon of Toho’s late-sixties kaiju.