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池上本門寺 御会式Ikegami Honmonji (池上本門寺), which is an 8-minute walk from Tokyu Ikegami Line Ikegami Station, is the largest Nichiren Buddhist temple in Tokyo, and one of the most prestigious temple in the metropolis. For details about this temple, see the article on Ikegami Honmonji Temple.
The Oeshiki held at this temple in October is an event to commemorate the death of Sect founder Nichiren (1222-1282).

Oeshiki

Oeshiki (御会式) is a series of ceremony commemorating the anniversary of sect founder Nichiren's death and is held from 11th to 13th of October. The most important rite in this event is the ceremony held on the morning of Oct 13, but for visitors, the huge mando procession conducted on the evening (around 6pm - 11pm) of October 12 is what-to-see. In this procession, about 3,000 participants towing a hundred and several dozen illuminated Buddhist-tower-like floats head for the temple for about 2km (1.2 miles) from around Tokyu Ikegami Line Ikegami Station in the south.
Note that on this evening, not only cars are blocked, but along the procession route around the temple pedestrians are also forced to go one way, which means you cannot get out of the temple from the main approach (south approach) and you cannot get in from behind (north approach.) So, though this temple is also approachable from Toei Asakusa Line Nishi-magome Station, approaching from Ikegami Station is recommended).

Mando procession
お会式
お会式
お会式
お会式

The route of mando procession

A mando is a small illuminated float imitating a Buddhist tower decorated by paper flowers. It proceeds toward the temple accompanied by matoi flags and the sound of uchiwa-daiko drums and gongs.
As shown on below map, mando floats proceed from three directions (south, north & east) and merge at south , heading for the main hall of Ikegami Honmonji Temple. The road shown in red is where pedestrians are forced to go one-way.

Ikegami Honmonji Temple Official English website
1-1-1 Ikegami, Ota-ku, Tokyo MAP
Access: 8-min walk from Tokyu Ikegami Line Ikegami Station
Area guide around this siteArticle on Ikegami Honmonji Temple