The player moves a character through two-dimensional fields, interacting with and examining various objects. The game can be saved by interacting with Petecan, a stuffed red bull.
Just like it's predecessor, it's mostly an exploration game, where the player walks through the school getting information about paranormal incidents. During the climax of the routes, your choices will affect the ending.
Turns out Moe never confessed to Guro, Keith or Charlie in Blood Soup and it was all a dream. Actually, they're all classmates and part of the paranormal club. At school, they find out about some mysterious disappearances and alien abductions. So they decide to stay late at night at school to find the truth.
An average schoolgirl who likes manga, yaoi and psycho boys. While very kind, sometimes to the point of naivety, she can be reckless when pursuing the boy she loves.
A cheerful boy who likes manga, cooking and cute things. He's also a proud pervert and likes to talk about his fetishes out loud, much to the annoyance of his friends.
A blunt and rude boy, but has a caring side and is very interested in alien conspiracies. He gets easily annoyed at Guro's antics and the two are constantly taking shots at each other.
A stoic and mysterious boy. He doesn't stay up late at school to find about the mysterious disappearances, claiming that he has something else to do. But in the end he ends up helping his friends. He's also interested in Moe and is very open about it.
Depending on which route you choose, you'll have very different endings. No matter what, the player will see how unraveled they were from the beginning.
If Moe chooses to go with Clyde, she ends up discovering an alien spaceship when she finds an army of Petecans and an alien boy named Masarou (from Masarou Comet), who's searching for his lost son Gasarou. Gasarou is a human-alien hybrid, born from Clyde impregnating Guro with Masarou's dna. Just as Moe releases the boy, Clyde appears, revealing himself to be an alien as well. He orders Moe to put Masarou back in the pod.
- Ending 1: Galactic Love
If Moe chooses to help Clyde, Masarou reveals that Clyde is an evil alien sent to monitor Earth and treats Masarou's race as slaves, but Moe ignores them. Clyde has enough of their interferance and drags Masarou and Gasarou back in their pods. Afterwards, Moe decides to live with Clyde in his spaceship forever.
- Ending 2: Free from Evil
If Moe chooses not to help Clyde, he has a motive rant telling her about his motives. Turns out he was sent to monitor Earth by his superiors and fell in love with Moe after seeing her rescuing a dog when she was a child. Clyde wanted to be with Moe, so he disguised himself as a human and rewrote the memories of the school to make everyone believe he was always a student there. Moe and Masarou escape and he's able to reunite with his lost son, Gasarou.
If Moe chooses to go with Keith, Clyde goes missing and go search for him. On the way, they find Lotte, a fellow classmate and Keith's childhood friend. Keith decides to search for Clyde again so Moe has to choose between helping him or staying with Lotte.
- Ending 1: She Belongs with Me
If Moe chooses to go with Keith, they go to the boys's bathroom, when they find a corpse and a bloody axe. Clyde bursts from one of the stalls and attacks Keith. He reveals Keith tried to kill him out of jealousy that he was closer to Moe. She defends Keith, causing Clyde to snap and murder Moe, under the pretense that if he won't have her, no one else will.
- Ending 2: Dissected Frog
If Moe chooses to stay with Lotte, they talk about their feeling for Keith. Moe notices Lotte is very obsessed with Keith and is hiding a scalpel in her pocket, with the intention of killing her. If Moe decides not to snatch the scalpel, Lotte kills her out of jealousy that she's closer to Keith.
- Ending 3: Urban Legend
It goes the same as the above, but Moe chooses to snatch the scalpel. She kills Lotte in self-defense and hides her corpse in the library. Her death becomes one of the seven mysteries of the school, with Lotte's angry ghost haunting the library.
- Ending 4: Rush
If Moe chooses to stay with Lotte and doesn't mention about her having feelings for Keith, Lotte doesn't bring the scalpel. Keith returns, tells Lotte to return to her class and Moe notices his shoes are dirty with blood. She calls him out on this, causing him to reveal he murdered Clyde out of jealousy, feeling that he was closer to Moe than her. He then decides to kill Moe, now that she knows too much.
- Ending 5: Deep Love
It goes the same as the ending above, but Moe decides to confess her love for Keith instead of calling him out for the blood on his shoes. Both have sex on the library.
If Moe chooses to go with Guro, they find about a serial killer called Faceless is behind the mysterious disappearances at school. While investigating, they're attacked by Faceless, causing Guro and Moe to be separated while escaping from it. While searching for a place to hide, Moe discovers a secret room filled with corpses. As she's processing this, she hears Guro's voice from the door, pleading her to open it.
- Ending 1: Faceless
If Moe chooses to open the door the first time, she lets Guro in, but they're attacked by Faceless. Guro has a breakdown, rather shocked that Faceless is in fact real (as the rest of his ending show that he's Faceless in disguise). Faceless kills them both with a knife and Guro dies protecting Moe.
- Ending 2: A Real Monster
If Moe chooses not to open the door at first but then agrees, she opens the door, to see Faceless in front of her. He starts laughing maniacally and takes off his mask, revealed to be Guro. If she acts horrified, he reveals himself to be a serial killer and murders Moe.
- Ending 3: Blood Bath
It goes the same as the above, but instead of acting horrified, Moe chooses to stay silent. She says she doesn't mind the fact that Guro is a serial killer and declares his love for him. Guro smiles, saying that she's no going back for her anymore. Both have sex afterwards.
- Charlie has been demoted to extra due to being the less popular of the boys back in Blood Soup. He only makes a passing appearance at the beginning and decides not to stay up late at the school, claiming that he has to take care of his brother. It's unknown if Randy is a real person or a figment of Charlie's imagination like he was in the first game.
- The events of the first Blood Soup game are revealed to be a dream Moe had. Still, she was able to predict that Guro and Keith are serial killers.
- Guro is still perverted and sadistic, but he won't try to hurt Moe for pleasure if she accepts him, like his dream counterpart.
- Keith does end up killing Moe if she discovers that he murdered someone, but won't do it if she accepts him. However in Moe's dream he was a serial killer that targetted girls while the real one just killed one person. Keith was motivated by jealousy while his dream counterpart was motivated for love for his father.
- Masarou reappears from Masarou Comet. Turns out he was captured by Clyde shortly after returning to his planet and his dna was used to impregnate Guro, resulting in the birth of an alien-human hybrid named Gasarou.
- At the beginning of the game, Guro tells Keith about some dreams he had in which he's abducted by aliens and getting alien probes inserted in his butt. Keith silences Guro before he goes into more detail. A report in Clyde's spaceship shows that Guro was in fact abducted and the experiments on him resulted in the birth of Gasarou. Clyde was shown to be very disgusted by Guro's sadistic and perverted behaviour.
- Turns out the Petecan (the bull-like creature that works as a savepoint in the first game) is an alien creature that works as an informant to Clyde.