The best way to choose a topic for your research paper is to browse your readings and other publications about Japanese society and culture until you find a topic that interests you. Below you'll find some resources to get you started.
Per your syllabus, possible topics include (but aren't limited to) material culture, foods, taboos, pollution, gift exchange, rituals, animal categories, bodily symbols, beauty, magic, power & status, measurement, gender, kinship, identities, art, birth, schooling, work-life, marriage, ageing, death, and the after life.
The Cambridge Companion to Modern Japanese Culture by 
Routledge Handbook of Japanese Culture and Society by 
Introducing Japanese Popular Culture by 
An Introduction to Japanese Society by 