this wont be spoiler.(in my opinon) this illust is based on side story, 鉄賽剣. (post #614763)
rumia and reimu 's relationship was mare "cannibal youkai and hakurei's miko" until episode 2. now, it is at least "friendly youkai and hakurei's miko". how they gradually get along with is one of the good scenes of this story, I think.
by the way, buront and reimu's relationship is "tenant and landlord" yet. it needs more and more time.