To summarize, Katsuki Bakugou had just turned eight years old, so he had just discovered he was an alpha. When you turn eight, it is the age where people discover what they are, whether they are omegas, alphas, or betas. Katsuki feels proud to be an alpha.

A child who is alpha. Katsuki is a 8-year-old boy who dreams of being the number one hero. Now he was letting out explosions playing with his own quirk "hah, I'm amazing! damn!" Bakugou says without controlling his tone.