Hasegawa has a personal history with Hisashi Mitsui. In junior high school, he faced Mitsui's confidence as well as his own inability to beat him in a match. Later on in high school, he encountered Mitsui again after the latter had become a delinquent and was shocked to see how much he had changed. They met again in the last match of the Kanagawa Interhigh Tournament, when he offered to mark Mitsui personally in a box-and-one.
There, Hasegawa brought his memories back and marked Mitsui relentlessly, but to no avail, as Mitsui had already managed to turn the tide of the match for Shohoku. His words ("don't underestimate high school basketball") made Mitsui think about how much he could not let his efforts be in vain. Before the match, Hasegawa stated that he would hold Mitsui to no more than 5 points. Having accidentally overheard this, the reawakened Mitsui went on to score 20 points, including five consecutive 3 pointers in the second half, to erase Shoyo's 12 point lead over Shohoku.