Kitsune no Yomeiri (a Touhou LW original) means the fox's wedding and refers to a sunshower. This term is used in certain parts of Japan, while the more generic term is tenki ame, which is Yukari's temperament. That makes this temperament a perfect fit for Ran, who is both Yukari's shikigami and a fox. Ran is endowed with Metal Phase, from her sincere dedication to her duties, and Moon Essence, from her true nature hidden within. The cold and silent Metal Phase resists Earth Phase, because earth bears metal, but it is weak to Fire Phase, because fire refines metal. The cooperative and indecisive Moon Essence resists the alluring and arrogant Sun Essence, but it is weak to the diverse and uncooperative Star Essence.

In Ran's case, the ability to use shikigami means the ability to control Chen. You could call shikigami a kind of pattern―like software for the computers used in the outside world. Ran herself is Yukari's shikigami, but she has Chen as her own shikigami too. Software allows a computer to do something it could not originally do, so youkai possessed by shikigami can do things they normally would not have been able to, but it also stops them from doing other things at the same time. If you want to know more, you should ask Yukari.