In the world of shonen anime, plenty of characters go through a satisfying and meaningful character arc. This allows the best shonen characters to end their life's story on a thematic and memorable note, such as Edward Elric retiring from the state alchemist life or Naruto Uzumaki becoming Hokage. Unfortunately, other shonen anime characters had their own arcs end too soon or end the wrong way.
Source:https://www.cbr.com/shonen-anime-characters-never-got-proper-conclusions/