Well, with what it was, I don't think it was a complete assimilation into the Samurai way, but rather just an adaptation into it from his previous experiences. Like as far as philosophy and whatnot, he already had it there, his stay with Katsumoto just clarified it.

Go to a bookstore or an online one and buy the book "Hagakure". You will understand the samurai way in the time it takes you to read it. If you need more incentive too, when I went to boot, they said I could bring one religious book, that was my choice. I got grief about it being religious and told, not my instructor 'cause he would've just ripped it up and pissed on it, but told the administrators, or the "other" people that I was a Zen Buddhist and if they were ones as well, I would hand over the book. One particular phrase in the book sustained me through BC, "The Way of the Samurai is in desperateness. Ten men or more cannot kill such a man. Common sense will not accomplish great things. Simply become insane and desperate. In the Way of the Samurai, if one uses discrimination, he will fall behind. One needs neither loyalty nor devotion, but simply to become desperate in the Way. Loyalty and devotion are of themselves within desperation."