If u noticed there are alot of similarities that u see on different shows such as One Piece, Naruto, Bleach, DBZ, etc.
|One Piece||Characters share personality traits||Both protaganist characters have very similar personalities||Swordsmanship plays a big role in the story|
|One Piece||They have perverts||They have perverts||Once again, they have perverts!!!!!|
|One Piece||Characters have a line of signiture attacks||Friends of the protagonist share same traits i.e. usopp and krillin or zoro and piccalo||Both have a small group of people fighting an organization i.e. ichigo and friends vs. soul society, SH vs. Baroke works|
|One Piece||They have awesome Opening theme songs!!||The protaganist always fights the strongest villian||Character's attacks have different power levels i.e. gear 2nd- gear 3rd and shikai- bankai|
|One Piece||They have had to overcome a challenge, hardship, or lost of a loved one||Romance seems to be downplayed and unnoticed alot||There are multiple groups and species i.e. OP has humans fishmean and giants, Bleach has humans, arrancar, and visors|
But i think that One Piece and Naruto have more things refferenced from each other like the 2 year time skip kinda reminded me of the 2 or 3 years naruto went away to train with jiriya and how the 5 great kage summit reminded me of the reverie. What else have u seen in common with OP or some other manga.