Abe has battled the disease ulcerative colitis for years and two recent hospital visits within a week fanned questions on whether he could stay in the job until the end of his term as ruling party leader, and hence, premier, in September 2021.

from Times of India https://timesofindia.indiatimes.com/world/rest-of-world/japan-pm-shinzo-abe-set-to-resign-citing-worsening-health-media/articleshow/77798296.cms