A sister-in-law who is cuter, more energetic, and brighter than my wife. Although she is someone I must absolutely not touch, what if I find myself in a situation where I can't maintain my male rationality? I just have to do it without my wife finding out! My romantic feelings with my wife have already collapsed after marriage, and I thought feelings like that were gone... Wouldn't you also like to cross a dangerous bridge by watching this work?