With regard to his character, Matsuzaka said that it was actually fun to be in a position to drive the people obsessed with their desires and evil to their deaths. However, he got too immersed into his role that his co-stars commented that it was tough to approach him. Sawajiri revealed that there was a frightening aura surrounding Matsuzaka as he became so much like Usobuki while Mamiya said that due to Matsuzaka's height and constantly being in Usobuki's clothes, he became really conspicuous and hard to miss on the set. Ashina then followed up by saying that Matsuzaka looked exactly like the character in the manga while Yada said that she was overwhelmed by seeing how Matsuzaka switched between his true self and Usobuki so easily. During the event, whenever Matsuzaka, Arata and Mamiya spoke, the audience was full of squeals of delight which led the director to say that he didn't have the intention of making a movie which could ignite such a response so it was refreshing and touching for him to see the audience's reaction.
In the movie, Usobuki had a signature line which mocked humans for being stupid thus the cast were asked if they had done any silly things so far. Mamiya said that there was once when he was too obsessed with checking out how a seed germinated and caused the plant to wilt while Sawajiri moved to a new house and bought a new car but found to her horror that the car wouldn't fit into her garage. Arata revealed that he burned himself when he heated milk in the microwave while talking to his mother. Matsuzaka then said that his example was about his silly thinking rather than an action. There was once when he was walking near the junction of Yarigasaki and saw many people on their skateboards. As he was thinking to himself that it was dangerous to be playing on the skateboards there, he was wishing silently that these people would fall down. When it really happened, Matsuzaka was mocking those people deep down for deserving it. This led Sawajiri to tease him for his "evil" thinking as Matsuzaka "repented" over his thoughts then.
Sources: Natalie / Eiga.com