(Onmyoji) The Diviner Saves the World

Serious version: Inside the citadel, Liming sat in the seat of honor, quietly watching the swords gathered in front of her. Heshikiri Hasebe: "So this is the point where this world deviates. What do we do next?" Tsurumaru Kuninaga: "Well, this is certainly a surprise. The Time Retrograde Army was hiding here all along." Honebami Toushirou: "Then let's start here." All the swords nodded together, then began discussing countermeasures in a jumble of voices. Heshikiri Hasebe: "Then it's settled. We leave tomorrow. This meeting is adjourned!" The swords: "Yeah!" Then some dispersed while others withdrew, and soon not a soul remained in the room. Liming, still sitting silently where she was: Who am I? What am I supposed to do? Why am I here...? It seems like I don't serve any purpose. In short, it's a story about a character's swords taking their Master through various worlds to eliminate the Time Retrograde Army. Note: A crossover with multiple anime series, clean romance, pairing undecided, but definitely 1v1. P.S. The protagonist looks incredibly useful, but actually...