An enlightening bit from his reflections after finishing YYH:
"I believe that anyone who draws has the desire to attract people with their art, but this is an ambition that I had suppressed for a long time. This is because back when I had just had my debut, my editor at the time had shown me a manga page by Hagiwara Kazushi (BASTARD!!) [
example]. I felt that if I were honest with myself, my art would never be able to compete with something like this. But I was never able to throw away my ideal of being able to draw manga without help from other people. A few times during the run of YYH, I finished my manuscripts all by myself. All of these instances were when my stress levels were at their highest. I don't know if anyone will understand, but when I was stressed because I wasn't satisfied with my manga, the only way for me to relieve this stress was to draw all my manga by myself.
As a result, those chapters ended up horrible. Both the characters and the backgrounds were messy. The one-shot Two Shots, Karasu vs. Kurama, Yusuke vs. Sensui, the scene where Yusuke meets Raizen, I drew most of those alone. The latter two were finished in half a day before my deadline, as a reader guessed and criticized in a letter. This might mean I fail as a professional, but I was satisfied. I had already started to think that no matter what anyone says, no matter how messy the finished pages are, I just wanted to draw this by myself, and I had no reason not to go through with it."
He also had this volume comment:
He was definitely hard on himself.