He is the Head of Personnel in Yotsuba. He is a very paranoid person, and always keeps a close eye on others.
Shimura's ability to pay attention to small details allowed him to join the meetings; he noticed subtle changes in Namikawa's face during his phone call with Light, who was pretending to be L. How to Read 13 states that he does not like his predicament.
A little over five months after L's death, he is killed by Light along with the other remaining Yotsuba Group members, dying of heart attack. In the Rewrite special, he is controlled and he is run over by a train.
