Shijou Saikyou no Deshi Kenichi, The Breaker: New Waves Recommendations
Both are about martial arts. The protagonists are somehow similar. New Waves has less comedy and is darker.
bot have someone who is bully and wants to be stronger.
1.Incredible stamina. Both protagonist males are almost unnbeatable
2.Martial arts learning speed.
1.Romance. Shijou Saikyou no Deshi Kenichi is male inlove with female. The Breaker: New Waves females fall inlove with male.
You should first start with the prequel, otherwise u wont understand majority of the things.
both are similar excluding comedy from New Waves, protagonists in both series find themselves being trained by World's best teachers.