Azulie

Azulie is the family ship between Azusa Aizawa and Rosalie Aizawa from the I've Been Killing Slimes for 300 Years and Maxed Out My Level fandom.

Canon
Azusa and Rosalie are not sisters by blood. But after Azusa helps Rosalie find a place to live, Rosalie starts calling Azusa by 'sis' meaning she thinks of her like a sister. Azusa accepts the fact that Rosalie calls her sis. Because she has two adopted daughters that had found her one day, and from now on called her mom. And Azusa was thrilled to have finally started a family.

Rosalie is the last main character to meet Azusa. She meets her after making Halkara, another person living under Azusa's roof, to come home one day complaining about how theres a ghost in her factory. Halkara makes medicine in her factory. Azusa at first claims she wants no business with the ghost, but when she is begged by Halkara, she gives in, but says she'll have to call a helper, that helper being Beelzebub. Beelzebub is a magical being that Azusa happened to meet; that was unafraid of ghosts.

After summoniong Beelzebub — she accidentaly summons her in a freezing cold bathtub — Beelzebub agrees to help catch the ghost haunting Halkara. The trio catch the ghost who happens to be Rosalie, who explains that Halkara's factory used to be a home, Rosalie lived their with her family... and after realizing her family were going to sell her off for money, she commits suicide, becoming a spirit bound to the house which soon became a factory for medicine. Beelzebub mentions that if Rosalie ever wants to be able to roam free, she would need to possess someone, that someone is Halkara, who is forced to be possessed by Rosalie. After possessing Halkara, Rosalie finds out that if she doesn't get out of Halkara's body, she would ultimately kill Halkara. This causes Azusa, and the rest of her family to try and force Rosalie out of Halkara's body, which fails each time until they finally come up with an idea to make Rosalie pass out, getting her out of Halkara's body.

Rosalie is forced out of Halkara's body, and realizes she doesn't need to possess anyone to move around, as she isn't a bound spirit anymore. Noticing Rosalie has no place to go, Azusa offers Rosalie to stay at her house. Rosalie cries and happily accepts, thanking Azusa and now calling her "Sis" short for sister.

Fanon
Azulie seems to be an unpopular ship within the Slime300 fandom. Even though the ship is canon. This may be because the anime is an unpopular anime, or just because people don't like it. Rosalie did attempt murder, and that may turn some people off. Luckily, with Azulie being an unpopular ship, there isn't much hate.

Trivia

 * Rosalie would technically be older than Azusa with Azusa's Human age, but Rosalie would be younger than Azusa with Azusa's Witch Age.