Whatever the belief system or whoever they're dedicated to, shrines have a way of making you contemplative. Check out Hanazono-jinja and share a quiet moment with the locals.
This sacred place in Shinjuku is popular with fellow travelers, so make a spot for it on your travel plans. Don't think the sightseeing ends there, however. There are a lot more spots waiting for you to discover after Hanazono-jinja. Tokyo Skytree, Tokyo Tower, and Tokyo Imperial Palace are not far away.