Piikan (a Touhou LW original) refers to a clear blue sky. This is an apt temperament for Reimu, the blue shaman from the world delirious with eternal summer. Her original temperament (strong against Sun Essence, Metal Phase, and Earth Phase, but weak to Moon Essence) has combined with the temperament of marine activities (strong against Fire Phase, but weak to Earth Phase). This cancels out any resistance or weakness to Earth Phase.

The ability of Reimu Hakurei (F1) from the world delirious with eternal summer (a Touhou LW original). Her ability doesn't seem all that different from the F1 Universe Reimu's. The F1 Universe interworld travelers are known by many names, such as the pro interworld travelers, the true interworld travelers, or the official interworld travelers. You can barely talk about interworld travel without mentioning these girls. And now, they have come to investigate this world of eternal summer. Tiny Yukari strongly suspects that the world of eternal summer is the main world in a series of approximately twelve parallel worlds whose temperaments have all been altered by the same mastermind. This means that by defeating this one mastermind, they might be able to resolve twelve massive incidents at once. Talk about efficiency. There is a very high chance that this mastermind is separate from those behind the Lost Word Incident. So, if all goes well, they hope to turn her into an ally. Her ability to influence multiple worlds sounds incredibly useful, and it's hard to imagine that she hasn't at least had some contact with the Lost Word Incident masterminds, so she probably possesses info that could be used against them. Of course, as a human and a shrine maiden, Reimu wasn't going to show any mercy. She'll suitably punish her for causing an incident, and only then will she use her for all she's worth. Reimu knew from experience that beating the bad guy up tends to resolve everything in the end, so she wasn't at all worried about her approach. All that is to say that there was no problem with her going all out and enjoying the Yin-Yang League. Out of all the parallel-world Reimus, the blue shaman is actually one of the more serious ones, but even she loves to have fun and play. By participating in the Yin-Yang League, she gets to have fun while working to resolve the incident at the same time. She vaguely remembered that battles of bullets were originally like that, too, which only made her more excited. No, she was super excited. How long had it been since she was actually allowed to have fun? The first rule of the Yin-Yang League is that those who get hit too many times where it hurts are eliminated! Where's that, you ask? In the feelings! No matter how many hits someone takes to the body, they are only counted as grazes. (This would be completely broken in battles of bullets.) You can think of it like a special kind of barrier, like extra layers of clothes or armor that let you continue the fight even if they get destroyed. However, if you do get hit in the feelings, you lose a life! In another game, it would be called hit points, not that Reimu would know. All she has to do is protect herself from getting hit while relentlessly going after her opponents. The Yin-Yang League is hyped up as some kind of sports tournament, but the most efficient way to win it is by destroying all the competition! "You know what we gotta do, Umikarao! It's time to unleash our ultimate shot! We'll score such an impressive goal that they'll lose all the will to fight!" After the match, Reimu and her Foundling stood side-by-side on the beach, staring at the setting Sun. "Umikarao... No, Tajikarao... No, Suika Ibuki." "..." "Are you having as much fun as I am?" "..." "Hehe, I see." "..." "One day, we'll bring it all back―everything we lost on that fateful day. I promise."