Sensei

"I know everything about you, and I know... you want a girlfriend."

Sensei talking to Katagaki Naomi.

Sensei, is a strange male character and part of the main cast of Hello World. In truth, he is the future version of Katagaki Naomi.

Personality
Sensei is a serious man and almost an all knowing personality. Due to his age gap to his younger self, Sensei is more confident and seeks to accomplish his goal with any means necessary.

Appearance
Sensei almost looks like Katagaki Naomi but older and taller. His brown eyes have shrunk and a scar on his right temple is noticeable. His hair is messier and his facial expression can also differ given some circumstances, but he's mostly seen with serious expression.

When he accessed the quantum storage device ALLTALE, Sensei wears a white combination of hooded coat, a polo shirt, white jeans and white shoes. After returning to his world, Sensei wears his white researcher coat, black long sleeve polo shirt, black trouser, and black leather shoes. He hangs his ID on his left chest, and uses a forearm crutches to support his disabled right leg.

Summary
In his hope to revive his girlfriend, Ichigyou Ruri, from her brain dead state, future Katagaki Naomi dived into ALLTALE to retrieve her recorded data. He met his younger version at Fushimi Inari-taisha at the beginning of his journey and guided Katagaki Naomi on how to get closer to the loner bookworm Ichigyou Ruri with his "Perfect Manual". Sensei also gave him the Good Design in preparation for the incoming the Fireworks Festival accident and prevent the "death" of Ichigyou.

Although Homeostatic System had been keeping watch of his movements, Sensei still kept it secret to Naomi. Ultimately, Katagaki Naomi changed the course of his timeline before the cancellation of the Secondhand Book Fair, in which Sensei also stepped in to help. Still, Ichigyou Ruri fell in love to Naomi but the timeline itself have shifted into a different situation.

On the night of the Fireworks Festival, Sensei and Naomi prevented her death with the latter's mastery of Good Design. However, Sensei turned against Naomi and took Ichigyou Ruri into his world to revive his girlfriend, but fate didn't side with him. The Homeostatic System 's fox men arrived to eradicate the foreign object - Ruri herself. However, Katagaki Naomi arrives for her rescue and took her away to safely return to their world. To repent for his sins, Sensei assists them on their way to the Grand Staircase.

But then Sensei met his end after the Homeostatic System impales him and asked Naomi to erase him. Sensei's last words wishes Naomi to be happy with her.