The music cafe scene was filmed at Lion Cafe, a tiny cafe in Shibuya, Tokyo, where classical music fans gather to sit quietly and listen to music.
WAM is part-robot, part-puppet. It was designed and built by Legacy Effects, who has done the special effects for a number of blockbusters, including Jurassic World (2015), The Jungle Book (2016), and Captain America: Civil War (2016). WAM took two to six people to operate, depending on the shot. Two people controlled its wheels and facial movements, via remote control. And two to four people puppeteered the arms in gray suits, the puppeteers who were later removed with visual effects.
Actual Shinto priests performing a blessing ceremony at the Konno Hachimangu Shrine in Tokyo were filmed.
WAM was part animatronics and part puppetry, according to Paul Weitz. In the first practice sessions, it was a big "hand-talker," illustrating each thought with a gesture. Weitz had to direct the robot to "calm down".