This was my third time contributing in an event hosted by ESEAP, a collaborative organization for East Asia, Southeast Asia, and the Pacific region. At ESEAP 2024 Kota Kinabalu , I presented my personal experiences , but this time I was glad to be able to talk about collaboration. And what was most wonderful was that 13 people from Japan contributed this time, and both young and veteran contributors were able to share their experiences with Wikimedians from other countries. I truly feel that accumulation is important in everything. Internatiolan Collaboration for the Yokohama Editathon On the afternoon of May 15th, the first day of ESEAP 2026 held in Kaohsiung, Taiwan, I gave a presentation about the Yokohama Editathon together with three other young Wikimedians. The Yokohama Editathon is an editathon where contributors upload articles related to Yokohama, a port city in Japan, to Wikimedia Projects, and it was held in Yokohama last autumn.…