Complex sentence: The site also notes that the limited use of the Dying Will Bullet in the fifth volume allows the author to develop Yamamoto's character and that the introduction of antagonists in the eighth volume proves he is "worthy" to be a shōnen manga character.
Split into simpler sentences: The site also noted that the Dying Will Bullet does not appear often in the fifth volume, allowing the author to develop Yamamoto's character. The same occurs in the eighth volume, where the introduction of antagonists prove that Yamamoto is "worthy" to be a shōnen manga character.