Yamada already feels this growth, this crazy desire to attack our boi is the hormones. She is almost reaching the level of her namesake, Yamada of B Gata H Kei.
Worse than the voice changing is the voice not changing. There is a former UFC fighter named Anderson Silva. He is muscular but his voice is thin. My last comment.
@kaitouk166 He's Nigorikawa-kun, the love interest of the manga Yamada's been lending him, first seen in chapter 42. Since 49 Ichi's occasionally been hallucinating him as a manifestation of his inner chad. He also shows up at the very start of 57.
He's basically just there to make Ichi's debates with himself more interesting and easier to follow.