All SPOILERS are to be left UNMARKED.
Main Characters
- Voiced by: Kentarō Itō
The older of the Aizawa brothers and one of the protagonists.
- Childhood Friend Romance: He's known Nao for a long time, and they're an obvious couple right off the bat.
- Decoy Protagonist: He's portrayed as The Hero for the first half of the story, but then he gets captured and the perspective switches to Ryota.
- Heroic Willpower: This, plus the Power of Love, is why he's able to resist becoming Cellaria's pawn even after being infected by Scylla.
- Official Couple: Nao has already won Shuhei's heart since early on, with them getting married after the events of the story.
- Parental Abandonment: Lost his parents at a young age, leaving him to be Ryota's main source of support throughout their lives.
- Voiced by: Hideki Ogihara (teenager), Nana Inoue (child)
The younger of the Aizawa brothers and the other protagonist.
- Big Brother Worship: Ryota has always looked up to Shuhei, which leaves him lost when the latter goes missing.
- Beta Couple: While the game gives him multiple potential suitors, the anime pairs him up with Sayaka.
- Parental Abandonment: Same as Shuhei.
- Voiced by: Kumi Sakuma
Shuhei's girlfriend and one of the main heroines.
- Childhood Friends: With the Aizawa brothers. In the case of Shuhei, this doubles as a Childhood Friend Romance.
- Hospital Hottie: She's a second-year nursing student.
- Official Couple: Shuhei and her are pretty obviously an item, and even get married at the end.
- Rose-Haired Sweetie: She has pink hair and a kind and passionate personality.
- Voiced by: Yuki Masuda
Ryota's friend who serves as the other main heroine.
- Beta Couple: She gets together with Ryota in the anime.
- Voiced by: Marina Ono
- Voiced by: Junko Shimakata
A mercenary hired by another faction within the terrorist group that infiltrated the Aries station.
- Clingy Jealous Girl: The closer she gets to Ryota, the more jealous she becomes of his and Sayaka's bond.
- Voiced by: Yui Shoji
A member of the terrorist group that infiltrated Aries.
- Canon Immigrant: She was created for the anime, but was later brought into the remake.
- Heel–Face Turn: She follows Gale in joining up with Ryota's group.
- Ship Tease: She's shown to have taken a liking to Kazuhiko, with some obvious hints at them getting together.
Supporting Characters
- Voiced by: Natsumi Yanase
A strange young girl found within Aries.
- Luke, You Are My Father: Though the nature of her birth is unorthodox, she is, for all intents and purposes, Shuhei and Nao's daughter.
- Voiced by: Miya Serizono (original game), Yoshino Nanjo (anime and remake)
Sayaka's best friend who got trapped within Aries.
- Ascended Extra: The remake gives her a little more prominence than the original game did.
- Ship Tease: With Gale in the remake. Her part in the epilogue with the flower shop is modified to show him opening it up with her.
- Voiced by: Takehito Koyasu
Aki's older half-brother.
- Aw, Look! They Really Do Love Each Other: For as much as he and Aki argue with one another, it's shown that they do care for each other deep down.
- Crazy Jealous Guy: He has a crush on Nao, and he's quite jealous of not only Shuhei for being her boyfriend, but Ryota as well for how close he is with her.
- Ship Tease: There is a mutual attraction between him and Karen, and the possibility for a Relationship Upgrade is hinted at.
- Voiced by: Norio Wakamoto
The Aries station's second-in-command.
- Back from the Dead: In the games, by Nanami.
- Cool Old Guy: A reliable older dude who humorously refers to himself as "dandy."
- Luke, I Am Your Father: He's revealed to be Sayaka's father.
- Death by Adaptation: The anime has him Killed Off for Real before he could reveal his identity to Sayaka, while the games let him survive and be reunited with his daughter.
- Heroic Sacrifice: He seemingly dies saving Sayaka. Whether the death stuck or not depends on the medium.
- Voiced by: Takashi Nagasako
The leader of the terrorist group that infiltrated the Aries station.
- A Father to His Men: He cares a great deal for his subordinates, earning him their loyalty.
- Heel–Face Turn: After realizing the situation, he decides to join with Ryota's group
- Heroic Sacrifice: He dies saving Aya in the anime.
- Lima Syndrome: Downplayed. While he took Aya as a hostage, he treated her well like the others who didn’t resist. This continued when Cellaria shows her true self and he raises his life for her.
- Parental Substitute: He's pretty much Karen's father-figure.
- Ship Tease: With Aya in the remake, to the point of him opening up a flower shop with her.
- Spared By Adaptation: While his fate in the original game isn't stated, he's confirmed to die in the anime, while he survives in the remake.
- Unwitting Pawn: He comes to realize that he was being used by Cellaria.
- Voiced by: Chiharu Tezuka
An instructor at Central Military Academy.
- Big Bad: She's the true villain of the story, using the terrorists for her own gain.
- Walking Spoiler: It's almost impossible to talk about her without spoiling the story's twists.