I am not entirely sure as well but this is just how pieced their dialogues together.
Yatori- always been cast aside and ostracized for his form/looks and lack of power thus became greedy and wanted to be one with Akura-ou (they had a past together where Akura was nice to Yatori thus got attached)
Kuromaru - s/he does not trust anyone and thinks no one likes him/er, only trusts relationship via contracts, it was explained further and I think clearly in the chapters about his/er past
Yatori Kuromaru made a contract - Kuromaru understood Yatori, I guess so s/he went with it while Yatori has no powers to get to the mountain and merge with Akira, so he asked for help
Okununishi(?)/Boss god diva - he loves everyone? And is just utterly nice, he is all about love isn't he? So he wanted to help Kuromaru.
I could be completely wrong so if anyone can help, I would appreciate it as well.
Kuromaro is a woman
Can someone please explain the story of Kuromaru,
What happened with that mask guy Yatori? Were they dating and he cheated?
In Yomi underworld (please explain the whole arc)...
Around the time Yatori was dieing, Kuromaru said something to him before disappearing. What was that about?
Why did Boss god diva Talked with Kuromaru in his last moments, and what did Kuromaru asked about being human or something?
Thank you for anyone taking time to answer. PS I totally love the story, ending is great. Kuromaru needs his own manga, his story seems interesting.