He is Hajime Nagumo's father.
Shuu is a man in his early forties with a tall frame and short black hair.
Shuu is a loving father and husband that possesses many otaku habits.
He has a tendency to go overboard occasionally, which has resulted in him getting into trouble with his friends and coworkers.
Shuu was born when his parents were at a later stage in their lives.
When Shuu was in college, he disguised himself as a shrine priest during the New Year holidays. He was later reprimanded by the real shrine priests, along with a high school student named Sumire (who had also disguised herself as a shrine maiden on her own). The two of them initially thought they would be in trouble for posing as shrine workers, but their disguises were so perfect that the real priests thought that they were actual employees and were disciplining them due to thinking that they were slacking off on their duties. Shuu then blatantly claimed that he wasn't a shrine employee and lied that the shrine clothes was his regular attire. It was then that Sumire fell in love with Shuu, which prompted the two of them to start dating, and eventually marry each other. At some point, they had their first and only child Hajime. In addition, Shuu would eventually become president of a famous game company, to which Hajime occasionally helped him with his work.
When Hajime and his entire class disappeared without a trace during his second year of high school, Shuu, Sumire, as well as the parents of the other students, did everything they could to find them, but to no avail. Eventually, many of the parents gave up searching for them, but Shuu and Sumire kept on searching for their son without rest (much to the concern of their friends), and used whatever means that could (even joining online web boards that talked about other missing children that disappeared under mysterious circumstances). One year after he disappeared, Hajime suddenly returned home in the middle of the night. After a very emotional reunion with his parents, Hajime spent the entire night telling them about his adventures in another world. Afterwords, Hajime wondered if his parents would still love him after revealing that he had killed other people during his adventure, but Shuu and Sumire assured him that they would always love him. Hajime then followed up by having his wives Yue, Shea, Tio, and Remia, as well as Remia's daughter Myu, spontaneously appear in front of them, much to his parents' shock. After learning the nature of the relationship between them and Hajime, his parents became hysterical, but soon calmed down when Myu expressed her concerns that they did not like her based on how they were acting, to which they suddenly became more courteous and expressed their joy at her and the others becoming important people in their son's life, and welcomed them to their family. They spent the rest of the night seeing recordings of Hajime's otherworldly adventures.
- Sumire Nagumo - Shuu's wife. The two of them love each other very much.
- Hajime Nagumo - Shuu's only son. He loves Hajime and become's deeply distraught after he disappeared. Both Shuu and Sumire would imprint Hajime with their otaku habits (going so far as to make a list for him called "The Seven Most Important Things for an Otherworld Summoning").
- Tomoichi Shirasaki - Shuu's relationship with Tomoichi is similar to Yue's relationship with Kaori. They constantly get into confrontations with each other that stems from Tomoichi being annoyed with Shuu's eccentric personally, as well as the fact that he is jealous that Kaori treats Shuu with more respect than him.
- Shuu's surname "Nagumo" means "south cloud" (南雲).
- Web Novel - Chapter 229
- Web Novel - Chapter 247
- Light Novel Volume 10