Morenatsu/Heartwarming

One of the things that pretty much can summarize the entire game from start to finish, is a constant string of these. It's difficult to get far in the game without running into these, and more often than not they chain together. The game's few Moments of Awesome often are also these as well. There are some specific to certain routes, and others that are encountered regardless of route.

Tatsuki's Route

 * Tatsuki revealing that he's working on an airplane. The Heartwarming moment here is there he says that he made a promise to fix it so he could not only fly himself (something that, even as a dragon, he cannot do), but also fly Hiroyuki as well. It's implied he's been steadily working on this airplane in his spare time when not working on his dad for the last five years, just for Hiroyuki.
 * During the festival, Tatsuki winds up getting a little drunk again, but rather than just getting immediately frisky, he instead takes Hiroyuki aside away from the festival, where he confesses that he loves Hiroyuki, or at the very least, likes him very much. Considering how good of friends they've been during the entirety of the vacation, helping him work at his father's place by taking a part-time job there, the fact he's slightly inebriated doesn't tarnish the impact of his confession. The fact that Tatsuki's rather gentle with Hiroyuki on the first kiss despite his usual drunken behavior is impressive.
 * Picking the 2nd option I believe gives you the first sex scene, in which Tatsuki lets Hiroyuki top.
 * Doubling as an MoA, the second time Hiroyuki tries flying the airplane, and it works. While Hiroyuki's in it, Tatsuki asks him where he'd like Tatsuki to take him. Hiroyuki says he'd like to see the ocean beyond the mountain. And Tatsuki does just that.
 * During the get-together after the successful flight, Tatsuki takes Hiroyuki aside for a moment and tells him he wants to build a house for him. But that's not the Crowning moment, no, that happens when Tatsuki flat-out proposes to Hiroyuki right there by asking him if he'll live with him in the house he's going to build for him. All the while Tatsuki is trying to act stoic with a heavy blush on his face.
 * The night before Hiroyuki has to leave, Hiroyuki and Tatsuki go to a hillside to watch a meteor shower. After some discussion, Tatsuki starts to get a little amorous again. Hiroyuki immediately asks if Tatsuki has been drinking again. The answer? No. This leads into the second sex scene, which is in itself a crowning moment because of how gentle Tatsuki is, is also helped by the music which preceeds it (though the second scene itself is played in silence). Afterwards, they watch the meteor shower in each other's arms. It doesn't get much more romantic than that.

Kouya's Route

 * Kouya's concert, considering everything that has led up to this point, the climax of Kouya's storyline is extremely satisfying.