These are what we call the 'YMMV items.' Things that some people find in this work. We call them 'your mileage might vary' because not everyone sees these things in the same way. This starts discussions in the trope lists, a thing we don't want. Please use the discussion page if you'd like to discuss any of these items.
Fridge Brilliance: Sometimes it's hard to follow the slow plot, mixed in occasionally with dis-jointed flashbacks and with some episode that seem to have absolutely no meaning. Then all of sudden, the pieces of the plot fall into place, and it hits you.
Ho Yay: Yaichi & Masanosuke; in the beginning of the story you never know if Yaichi is going to kill Masa... or kiss him. The ending and opening are also very much love songs, and considering that they don't have other love interests and that their relationship is the driving force of the plot... well. Masanosuke is also constantly trying to find more about Yaichis past, and he's the only one to really gets Yaichi to drop his Stepford Smiler facade at points, which dropped completly in the last episode of the anime in a very sweet moment between these two. See You Are Not Alone for more.
The way Matsu warmed up to Masanosuke after being saved by him and showed his gratitude was also very sweet. Another example where we get a glimpse of someones emotionshidden under a mask. Masanosuke really seems to have a talent to get under people's skins.