BEWARE! MAJOR SPOILERS AHEAD!!!
Chapter 1: Welcome to the PROJECT
- In the anime series, he had the illusion that the appliances were alive due to his hikikomori. The manga reveals that it happens due to his drug intake
Chapter 10: Welcome to the HEAVEN
- In the anime, the [OFF] line group was to commit suicide by jumping off the cliff. In the manga, it was through oxygen starvation via burning coals inside a tent to consume the oxygen.
- The story about the rich man who once owned the island and commited suicide on the cliff was only added in the anime. In the manga, it was the oldest of the group who owned the island
- Akira Jougasaki makes no appearance at all in the manga, only having a cameo appearance in this chapter as the one who called Hitomi on her phone to propose the marriage. In the anime, Jougasaki makes a physical appearance.
- The plot in the manga is way far too different from the anime in many ways:
- Misaki had hidden listening devices at Sato's house (creepy...)
- No Jougasaki appearance
- Yamazaki brought Misaki to the Summer Comicon (ne?) instead of the Suicide Island
- No Jougasaki means no thrilling boat scene, no car ride.
- They took the train
- Despite grabbing fuel from the boat, they made it back with the boat
- Jougasaki made a phone call to the island
- Suicide method
Chapter 11: Welcome ONLINE
- Yamazaki revealed to Sato that he was Mia (or Mya in the Manga); Yamazaki planned to tell Sato about it in the manga.
- Toro Toro wears a wizard hat in the manga, while having a Gaara-like look in the anime
Chapter 12: Welcome to the LOCKED ROOM
- Exclusively in the manga
- Although, it does parallel some of Yamazaki's talking to Sato after revealing his character (especially the 30 years after sequence)
- Yamazaki in the anime but Misaki did the "30 years after" talk in the manga tho...
- Sato was locked in his room by Misaki for interrogation
- Manga implied Misaki was a highschool dropout
- Yamazaki revealed his identity here AFTER Misaki's interrogation... far from the anime
Chapter 13: Welcome to the BLUE BIRD
- Sato jumped from his unit... (not in the anime)
- He met Megumi while walking along with the crowd. In the anime, he was found due to their yearbook.
- Company name is "My Way" in manga, "Mouse Road" in the anime
Chapter 13: Welcome to MY WAY
- They had food tasting; only soap demonstration in the anime
- It was Sato's birthday (Spoiler: feels)
Chapter 19: Welcome to SELF-SACFRIFICE
- Jougasaki's first appearance in the manga