Touhou Doumeiju: Mystical Power Plant

Written by Milka Oyasu, the story centers around a giant tree that Kanako Yasaka has brought to the Youkai Mountain from the Outside World. She intended for said tree to serve as a symbol of Gensokyo's newfound age of ecology, and it was called the "Life-Guiding Tree" to reflect this. However, during the opening celebration, a mysterious light appeared around the top of the tree, giving off a strange power. This prompts teams of Reimu Hakurei and Utsuho Reiuji, Marisa Kirisame and Byakuren Hijiri, and Sanae Kochiya and Kanako Yasaka to investigate.