This study is in response to the question about how Japanese educators achieve such a high quality of instruction. Considering the area of lesson study has opened the door to new ideas and concepts that are not well defined and too broad to understand. Kyozaikenkyu is an aspect of lesson study that has been said to be a crucial aspect to successful lesson study. Kyozaikenkyu is done on a daily basis by Japanese educators; however, there is very little written about this process in relevant literature. This study examines what Japanese educators do during their daily kyozaikenkyu, and why they do it. Through interviews, observations, and participation in kyozaikenkyu, I have been able to describe a process many Japanese educators go through to prepare their lessons. There is a difference between what these educators do during kyozaikenkyu for a research lesson compared to the kyozaikenkyu of a daily lesson. I document two variations of daily kyozaikenkyu. One variation corresponds well to the kyozaikenkyu done for a research lesson, while the other variation is something new. This thesis expounds on those differences as well as explores the purposes and benefits of daily kyozaikenkyu for the Japanese educators that participated in them.