Professor Kagami

A great physicist who has worked a lot on the time travel of which Natsuki is a fan and who often goes into the documentaries she watches.

It's Nene's husband and Mimi's dad.

His passion for time traveling would come from a person he met in the past and who always ordered at a cafe the "back menu", a shrimp avocado bowl. He sometimes continues this little tradition when he goes to the same cafe today.
His research and works served as bases for the construction of the Nagi family's time machine.