Barrier teamReimu as a toddler and the gap youkai Yukari Yakumo. Yukari has witnessed Gensokyo's long history, and Gensokyo separated from the outside world through a barrier must have many things to do with Yukari as a gap youkai, so Reimu becoming the miko of Gensokyo must also be in her knowledge, if not her creation.
By handing the duties of a miko to Reimu Yukari also gives over the many youkai of Gensokyo.
Sitting on the back of Genjii Reimu has calmly accepted all of this. Genjii, Yukari, and the youkai all have long lives, but a young Reimu still has to grow to protect Gensokyo.
