This manga takes place in Gensokyou, the setting for most of the Touhou games. Touhou games related. It's story of 3 fairies and their daily tricking to visitor of Hakurei Shrine, getting revenged, and so on.

Sunny Milk, Luna Child, and Star Sapphire are three mischievous fairies that have special powers, setting them apart from other members of their kind. When they are not doing their usual pranks, they try to pass the time by engaging in activities within the vast magical forests, the Hakurei Shrine, or even the Scarlet Devil Mansion. As they live out their lives, the trio meets various humans, youkai, and other fairies—all of whom could be the next target of their comedic shenanigans. [Written by MAL Rewrite]

After moving into the large tree just behind the Hakurei Shrine, the Three Fairies of Light—Sunny Milk, Luna Child, and Star Sapphire—have more opportunities to continue their mischief than ever. However, now that they are closer to Reimu Hakurei, the youkai exterminator of Gensokyo, any move that incurs the shrine maiden's wrath will likely be met with terrible consequences. Despite this serious-sounding threat, the boisterous trio continue to use their quirky abilities to annoy anyone they target. Whether it be harmless illusions, inconsequential thievery, or even things that benefit Gensokyo's residents, the fairies' prankishness will not die down anytime soon. [Written by MAL Rewrite]