[Kristoffer O]

> He just seems to be of very limited overall usefulness

The Yama-no-kami never intended to make himself useful to a petty pretender upstart. He has been the ruler of his mountain for millenia, and he is very useful for the inhabitants of his lofty abode. Pretender come and pretenders go. No need to hurry away into a uncertain future in an inhospitable land making the same mistakes as most pretenders do, namely getting themselves killed by surprisingly stalwart defenders.