Akimitsu was ashamed when it appears that he is now on his own according to Raven's response to the note that was jotted down to him. Being irresponsible to the gang he is a part of isn't what he is expecting to see considering how absurd his behavior was and the outcome isn't pretty for him as a result. Besides, he is a rookie and a rookie can make mistakes.
Perhaps, cheering her up might be a way to loosen the anger for the two of them as he didn't want Raven to feel enraged because of him not obeying her orders sooner than expected. He doesn't want this to go on any further. He wrote a reply on the note and hoped for the best. He is starting to get a little irritated from this but not literally. He needs to remain as calm as he can handle. He doesn't want his ambition to climb through the ranks to be interrupted by his constant anger issues.
"I understand what you are feeling right now but we must stick together as a team. I may be a rookie but it doesn't mean that I am not capable of doing anything as a result of my behavior. There is still time for self-improvement but it may not be perfect for you. This time, we will get through this together. I just thought this might cheer you up a bit. Maybe not. Anyway, I'll meet you there. See you soon." He wrote.