This is based on opinion. Please don't list it on a work's trope example list.
Tear Jerker / Great Mazinger
In one of the final episodes, Sayaka wants go to fight, but Professor Yumi tries talking her out of it, reasoning DianaA is too weak to fight, and he does not want jeopardizing his daughter's life. Professor Yumi had been a somewhat distant father throughout Mazinger Z and Great Mazinger, but every so often he showed he truly cared for his daughter. This was one of those times.
Professor Kabuto begs Kouji as he is dying to treat Tetsuya like his brother. Instead of asking him why he is leaving him AGAIN, Kouji vows to do so.
After Professor Kabuto's death, Tetsuya is berating himself, thinking it's all my fault (he is right), and he vows he will never again feel petty jealousy as Jun watches over him.