Spirit Tortoise

The Spirit Turtle is a mountain sized turtle known to be a greater disaster than a wave of calamity. Motoyasu, Itsuki, and Ren break the seal restraining it's heart. Naofumi is left to find a way to defeat it. It is capable of firing intense lightning (electric-type magic) beam attacks as well using physical attacks including kicks and body slams. It is also able to summon Demon Bat familiars as well as many others including those that resemble Gorillas, Yetis, floating eyeballs, caterpillar-like familiars (they're not even named so I'll just leave them here) and zombies (residents of the city built on the turtle (should I give this a section in humanoid??)). Inside there are several more familiars that protect the heart. There are Mimic Type Familiars for path concealment and antibody-like familiars (once again not named) for removal of hazards. Deep within the turtle is the heart which is capable of using strong gravity magic as well as firing a high powered beam similar to the head but slightly less powerful to avoid damaging itself. Found in 『Chapter 116』 of the web novel.