WARNING: The following contains spoilers for Season 1 of High-Rise Invasion, now streaming on Netflix.
There's a lot of content packed into the 12 episodes that comprise Netflix's High-Rise Invasion Season 1. In fact, nearly 150 chapters are condensed over the series, which follows the journey of Yuri, Mayuko, and their allies and enemies in an abnormal skyscraper realm. Everyone's jockeying for power in order to get to the mysterious chopper and find a way out, leading to a lot of chaos and bloodshed along the way. With that in mind, let's dissect the many changes made from the source material for the anime.
The Anime Has Less of Rikuya's Crush
Rikuya can control masks with his mind, and he wants to form an alliance with Yuri and her brother, Rika. In the manga, he also has a crush on Rika that gets really weird as he keeps harping on his cuteness, among many other explicit things over the phone. The anime tones this down, though, and just focuses on Rikuya trying to gather them in one place, making Rika mostly preoccupied with wanting to save his sister.
The Manga Doesn't Show the Maid's Unmasking
Early on, Yuri is attacked by the Maid Mask -- an attempt by the programmers to convince Yuri to commit suicide. However, she shoots the maid in the head and cracks her mask, instead. The maid ends up jumping off the building but before that, we see her face -- a pretty woman that shows Yuri these people are mind-controlled, but human. The High-Rise Invasion manga didn't show her face, as it wanted Yuri to be colder towards masks.
Ai's Introduction Comes Earlier In the Anime
The main villain of High-Rise Invasion Season 1, Aikawa, is introduced earlier on in the anime than in the manga. He plots with Kusakabe and his other masks to take out the heroes and their alliances. Notably, Ai keeps laughing at people's names as he thinks they're ridiculous but the anime omits this to make him more serious.
The Three Students Missing From the Anime
In the manga, Yuri finds three students -- Nomura, Nishimura and Nozaki, and Nishimura then stumbles upon and starts wearing the Machete Mask out of curiosity. This causes him to kill his colleagues before being murdered, but the anime doesn't include this as it doesn't want Yuri finding out too much about what masks can do to normal humans in the onset.
Yuri's Journey of Discovery Is Different In the Anime
In addition to the students, Yuri found a severed head during her explorations, which scared her in the manga. She was further weakened by Rika also calling to tell her the details about the masks wanting to make people commit suicide. The High-Rise Invasion anime doesn't have any of this. Instead, Yuri discovers the masks' operations on her own. It also omits the severed head, as well as men and women jumping off the bridge to keep Yuri in the dark.
The Mafia's Deception Happens In a Different Place In the Anime
Yuri and Mayuko are duped by a mafia group into coming to a building via a flyer. The flyer said that help to suss out the masks' objectives was around. The manga had this group holding them hostage and then moving to another building to assault the girls, but the anime has it all occurring at the same spot. Interestingly, Mayuko would also put on a mask in the bathroom to save Yuri, but in the anime, she puts it on in that same room and powers up.
The Anime Adds More Flashbacks
The manga has Mayuko getting into her daddy issues a lot more, while the anime dials it back. The anime also adds in a lot more flashbacks with Rika and Sniper Mask to show there's a bond that connects Yuri to Sniper, too. The manga didn't focus much on this at all, preferring to keep the mystery up. In addition, when Sniper's mask malfunctions, the High-Rise Invasion manga has him just hearing the programmers' orders fading while the anime shows them in their digital constructs. One of Yuri's other soldiers in the blade-wielding Zwei also sees ghosts from her past, which the anime doesn't include.
How Megumi and Monk Differ In the Anime
Megumi and the Monk Mask (sent by Rikuya) are key in helping protect Rika's crew. In the High-Rise Invasion manga, Monk does a lot more killing compared to the anime. As for Megumi, she actually has more of a crush on Rika in the manga, desperately trying to get his attention, but the anime keeps her in the background.
The Great Angel Is Much Scarier In the Anime
The pint-sized soldier in the black wetsuit, Dai, is mind-controlled by Ai as he holds the most power of all masks. Ai seals this power, though, making Dai into more of a slave, only unleashing him in full when it's time to attack Yuri and her people. In the anime, the Great Angel is much bigger and more imposing when he hulks out, which feels scarier and more dynamic in motion than on a manga page.
The Anime Improves Kusakabe's Identity Reveal
When Kusakabe and the Great Angel go after Yuri's team in the High-Rise Invasion manga, they use humans as shields. Kusakabe laid down cover fire, but the manga spoiled her identity by revealing Uzuki (a kid with Sniper and Yuri's team) knew she was actually his mom. He contemplated for a while how to tell the crew, but the anime changes this drastically. The villains use no human shields, and it's only at this point when Sniper's about to kill Kusakabe that Uzuki realizes she's his mom, creating more drama as he doesn't want her dead.
Rika Getting Masked
Lastly, Ai takes Rika hostage in the later episodes and even masks him up at the end of the season, all so Season 2 of High-Rise Invasion can likely start with Ai using Rika as an emotional, personal pawn. This doesn't happen until later on in the manga, which wants to prop Yuri's team up as victorious before they find out what Ai did to Rika. The manga draws it out more as it doesn't want to crush Yuri's happiness just yet.