Aikido Yuishinkai has its birth place in Japan, being founded by Koretoshi Maruyama, a direct student of the founder of Aikido. At one time sensei was the president and chief instructor of the Ki Society, before retreating to a temple for 10yrs of seclusion - after which Aikido Yuishinkai was founded.
It has a low profile in Japan, I suspect in part out of respect for other aikido organisation. Maruyama Sensei teaches in 2 dojo in Japan and numbers are kept small. The headquarters in Osaka for the district is headed by Okajima sensei who has been nominated as Maruyama Sensei's successor, who holds lineages in a number for other arts as well. The dojo itself is full-time, but small by western standards.
Tokyo, For class locations and times please contact Elisabeth aikidoyuishin@gmail.com , Koretoshi Maruyama
Osaka, Kansai District Headquarters, Atene Building 2nd Floor, 1-7-14 Ebisuhon Cho, Naniwa-Ku, Osaka-shi 556-0013, Taiki Okajima
Fukuoka, for locations and classes please contact Sachio Tazoe sensei, Sachio Tazoe