I don't get it either. My guess is as we know Yukari who creates Gensokyo is the future self of Maribel after some unbeknown tragedy. This comic shows how Reimu gets to the future (the past?) and prevents that tragedy. There is no Yukari, no Gensokyo, and therefore this is the last story.

So stupid I love it.

It's nice to see Nitori being badass for once. The art style is quite unique.

I love this series. It works so well because of how uncanonical it is. Yukari as we all know and love is the sage of Gensokyo. She's awesome, calculating, mystrious, mischievous, and heartless sometimes. Yukari here is a shonen protagonist. She is earnest, cute, fluttering, and kind. She cares for her friends and fights for whom she loves. And it's not like we can't see all these qualities reflected in our usual Yukari.

My only complaint is the author skipping Yukari-Yuyuko meeting. Understandable since that episode is already so famous. But I like how Yuyuko is drawn here, so more of her would have been appreciated.

I love the last line. This is always what I assume in their relationship. Keine is loving and caring, a better person for Mokuo than the princess. But all three know their relationship will not last, and Mokuo will end up with Kaguya eventually. It's also very sad for Kaguya as well, since she has to live through eternity knowing she is only the second choice of her love one.