This paper proposes multiscale service design method through the development of support service for prevention and recovery from dementia. Proposed multiscale service model consists of tool, event, human, network, style and rule. Service elements at different scales are developed according to the model. Firstly, the author proposes and practices coimagination method, which is expected to prevent the progress of cognitive impairment. Coimagination support system and program were developed as "tool" and "event". Then, Fonobono Research Institute was established as a "network" for "human" who studies coimagination, which is a multisector research organization including older adults living around university campus, companies providing welfare and medical services, local government, medical institution, researchers of the University of Tokyo and Keio University. The institute proposes and realizes lifelong research as a novel life "style" for older adults, and discusses second social system for older adults as an innovative "rule" for social system of aged society.