Tōeizan Kan'ei-ji Endon-in (東叡山寛永寺円頓院) (also spelled Kan'eiji or Kaneiji) is a Tendai Buddhist temple in Tokyo, Japan, founded in 1625 during the Kan'ei era by Tenkai, in an attempt to emulate the powerful religious center Enryaku-ji, in Kyoto.

Once a great complex, it used to occupy the entire heights north and east of Shinobazu Pond and the plains where Ueno Station now stands.

[3] What is today the temple's main hall was taken from Kita-in in Kawagoe (Saitama Prefecture) and transferred to the site of a former Kan'ei-ji subtemple.

[8] Tenkai wanted to create a powerful religious center and, to achieve that, he built Kan'ei-ji imitating Enryaku-ji.

[1] From then on until the end of the shogunate, Kan'ei-ji's chief abbots were chosen among the Emperor's children or favorite nephews and called with the honorific Rinnōjinomiya (輪王寺宮).

The revolutionary forces had occupied most of Tokyo, and Edo Castle and the majority of the Tokugawa troops had already surrendered, however one band of shogunate soldiers barricaded itself in Ueno with the intention to resist.

[8] They held the Kan'ei-ji's abbot in hostage, and maybe for this reason the Satsuma and Chōshū revolutionaries didn't attack immediately.

[6] On July 4, 1868 (Meiji 1, 15th day of the 5th month),[9] the final attack came and from early morning artillery rounds fell from Hongo's heights on Ueno.

[6] After a fierce battle, in the late afternoon the revolutionary forces broke through the defenses in the south at the Black Gate (the Kuromon), near what is today Ueno Park's entrance.