This is based on opinion. Please don't list it on a work's trope example list.
Tear Jerker / Inubaka: Crazy for Dogs
Any dog lover will bawl plenty while reading this manga.. The story usually is fun and cute, but times like Chizuru's old dog Ricky dies, right after she said something making the reader think she really didn't care whether he died or not had this troper bawling her eyes out. And of corse in the recent volume when Kanako's dog Czerny died and Kanako almost killed herself because of it. She went into a slight depression and tried to forget about it by drinking and going out with strange guys until Suguri suggested she get a new dog that owner had just been killed because of an earthquake. Couldn't stop the crying.