I tried to keep it simple, but it sort of ended up becoming elaborate as hell?? I'd argue that these aren't really emotions though...
The story kicks off with reluctance, acknowledgement, and reconciliation in mind. (Two siblings with an awful work dynamic between both of 'em gotta accomplish a simple task, knowing their faults need to be worked on together.)
It kinda carries on into the story as it develops where the two each have their own driving emotions. After completing the task, Mugen opens up a case related to it as he's driven by determination and compassion for the family involved. Haruka is exposed to her insecurities she tends to hide from herself and is sort of driven to join him out of regret for how she handled things earlier.
If I had to boil it down to super basic feelings, hope and remorse are probably it.