Much of these two episodes is padded out with the inclusion of the anime-original character Corporal Yamamoto, so it’s almost inevitable that this post will largely revolve around him. In the original novels, Yui is alone when she returns to the hangar to destroy the Type-99 cannon. In the anime, Corporal Yamamoto, a mechanic on the team, hangs back and winds up assisting Yui in trying to destroy the cannon. This expands the Soviet arc quite a bit, as Yamamoto’s new anime-original scenes dominate the second half of episode 11 and the first half of episode 12.
There are other anime-original scenes that expand the Soviet arc even more, such as new scenes of Yifei and Bao-Feng Flight (in the novels, they were introduced later in the Blue Flag arc, and were only indicated through dialogue to have been present during the Russia mission), as well as several flashbacks, of Yui’s trainee days in episode 12 and (skipping forward a bit) of Kyoko in episode 13. I like all of these additions to the universe, but in retrospect, I’m not sure it was such a good idea to stretch out the Soviet arc this much. Part of that is because I think Total Eclipse is best as a quieter, character-focused story, and while the Soviet arc does push Yuuya’s character forward in important ways, overall I find this arc to be one of the weaker ones, and having to go through so many episodes of it is kind of a slog. I dunno – if you’re more into the life-and-death battles with the BETA, maybe you might appreciate having more time spent on this arc.
I do like the idea of giving Yui an epilogue to the Kyoto story, by allowing her to put Yamamoto out of his misery after having failed to do so for Yamashiro. I appreciate that follow-up, giving Yui that closure. Is that really worth the equivalent of an entire episode to set up? I’m not sure.
The Total Eclipse anime wound up adding a number of new ideas and scenes to the story, and the game adaptation that came after incorporated pretty much all of them (although the game was already in production at the time, so it’s hard to say what was truly anime-original and what was already planned to be in the game and got incorporated into the anime during development). Yamamoto’s appearance here, surprisingly, is not included – I suspect it’s because, as I said, Yamamoto’s story is intended as an epilogue to the Kyoto story, and that story wasn’t included in the original release of the game.
That said, sometime late in development, the game devs got the idea of including a special nod to Corporal Yamamoto. Although Yamamoto does not appear in the game itself (like in the novels, Yui is alone in the hangar in the game), there is a specific nameless, faceless mechanic who appears several times in the game, during Yui-centric scenes. This character is supposed to be just some minor grunt character, but the creators decided to cast Taishi Murata, who played Yamamoto in the anime, to play this role. Neither the dialogue nor the in-game text box identifies the character, but the end credits do indeed list Murata’s role as Yamamoto. So this character, apparently, is a version of Yamamoto who did not stay behind at the hangar and wound up surviving.