Not yet. I plan on getting the manga once i settle in my new home. I'd love to get the novels but sadly there seems to be no official translation available (the fan version is pretty well done tho, so cheers to whoever dedicated their time and patience to provide us with it). Would also love a poster or something for my soon to be weeb corner. >>3258416
You won't regret it if you do.>>3258832
As far as the anime goes, it's probably that scene where he has to decide whether to tell Shion the truth about what he knows. It's been a while since I've watched it so I might be wrong about the timing of it. Nezumi's alone in his room and he just looks at the pair of mugs on the table. I love the way it was done, the message comes across without any explanations. He realizes that regardless of what happens, nothing will ever be the same should anything happen to Shion.
Another good part is the one where he is begging Shion not to pull the trigger. It's probably the turning point to their entire relationship because he comes to the awful realization that he's in love with his own image of Shion. Since people aren't ideal embodiments of what we yearn for, you can tell what happens next.
In the novels however, my favorite is definitely the "goodnight" kiss or rather what happens right after. I don't want to go into detail for fear of spoilers (since it's not explored in the anime) but it's the first time his defenses are completely down and he drops the act. No more Eve, no more vengeful antihero - just a lonely vulnerable kid. No idea why they removed it, since it goes a long way into showing his actual character and the development of their relationship (but of course, it would have ruined both the tsundere act and the BL tropes).
I never thought of hugging a fictional character before but that was the first time I felt awful for not being able to.