Doctor

博士

Doctor
Doctor博士 
AliasesDoc
Hair, Curtained, Grey, Short
Eyes, Blue, Hosome
Body, Adult, Pale, Slim
Clothes, Shirt, Trousers
Personality, Brave, Protective, Secretive, Smart, Watashi
Role, Friend, Scientist, Secret Identity, Widower
Engages in, Dimensional Travel, Time Travel
Subject of, Accident, Disability, Injury
Engages in (Sexual), Not Sexually Involved
Visual novelsSide character - Astraythem
Voiced byCamembert Juuendou

Description

<hidden by spoiler settings>The doctor that only Tsukumo knows his existence ...

He lost his wife and daughter in the disaster of 1996 and work with Tsukumo for their respectives interests.
They help each other to reach their goals.

He has many and different memories on Tsukumo but with variations. He remembers a Tsukumo with a yellow bandanna and another with a green bandanna.
He realizes that their time travel can also be interdimensional, and that he and Tsukumo may not be the first versions of themselves to travel back in time and exceed the dimensional limits.

He then develops his theory on "The complexity of Time" ...

Other instances

Professor Kagami
Professor Kagami加々見 教師 
AliasesPapa
Hair, Blue
Eyes, Blue
Personality, Funny, Smart
Role, Father, Husband, Scientist
Engages in (Sexual), Not Sexually Involved
Visual novelsSide character - Astraythem
Voiced byCamembert Juuendou

Description

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.

<hidden by spoiler settings>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.

Nagi Kyouichirou
Nagi Kyouichirou凪 鏡一郎 
Hair, Curtained, Grey, Moustache, Short
Eyes, Blue, Hosome
Body, Adult, Pale, Slim
Clothes, Necktie, Suit, Trousers
Items, Walking Stick
Personality, Secretive, Watashi
Role, Father, Friend, Non-blood-related Father, Secret Identity, Wealthy
Subject of, Accident, Disability, Injury
Engages in (Sexual), Not Sexually Involved
Visual novelsSide character - Astraythem
Voiced byCamembert Juuendou

Description

Kuurin's millionaire father.

<hidden by spoiler settings>Kuurin isn't his real daughter, he adopted her after the disaster of 1996, when he met her in a hospital. At that time, Kuuri was completely amnesiac, however, no man could approach her because she was having hysterics crisis at their simple mere sight.
Her body had traces of wounds caused by men, spread over a very long time. She had to be beaten.
They thinked she was probably "raped" several times in the past too.

Having forgotten her rape, his daughter continues to make nightmares every nights of her atrocious moments, but doesn't know and remember why when she wakes up in panic. He confided to Tsukumo his disengagement because he can not help her.