I know it’s not a manga scene, but I believe this is a classic just as much. As Ranma abd Akane plummeted toward the cure to his aquatransexuality, Ranma realized that if Akane touched the water as well, she would become a man. He knew that he couldn’t let it happen, because he didn’t want to see the woman he loved become a man (if you watch the subtitled movie 2, you’ll see what I mean) He powered his ki, and blew a whole through the island, making the spring wash into the ocean. He gave his cure up to save Akane.