Aqua

Aqua (アクア, Akua) is one of the secondary characters of Isekai Quartet. She is the Goddess of Water in the KonoSuba universe.

Appearance
Aqua possesses long blue hair and wears a blue dress.

Personality
Like her home series, Aqua is a childish and bratty Goddess that constantly seeks praise. Being rather blunt with her feelings and a bit of an annoyance to others, especially the Overlord cast due to their lineage. Having a hatred towards them and usually trying to attack, kill, or simply offend them. Being also prone to crying and is rather selfish at times. Thus calling for the aid of others.

Despite that she does have moments of kindness such as defending Albedo despite her being a demon when she was being made fun of being a virgin. Not to mention she knew that Ainz, Tanya, and Subaru were all from other worlds hinting at her intelligence.

She is also rather shameless when it comes to cheating. Ainz considers her a "tsundere".

Plot
She attempts to purify Ainz and his crew. She failed and was punished.

When the class does show-and-tell, she attempts to exorcise Ainz and his crew again, but is stopped by Kazuma.

She is put into animal care along with Subaru and Aura.

After revealing she is a goddess and that she has sent people to other worlds, Tanya prepared to attack her. Fortunately, Subaru and Ainz stop Tanya.

Powers & Abilities
As a Goddess Aqua has immense powers, particularly against undead and demons which the Overlord cast is composed of. Though its usually unused considering her bumbling nature and low intelligence. Not to mention her bad luck.

Turn Undead: A spell capable of purifying the undead and allowing them to enter the heavens. While Ainz states its a low level spell, because of Aqua's Goddess status the spell is far more powerful. She is able to cause serious discomfort to Ainz Ooal Gown, a powerful magic user with a single attack. Shaltear was also affected and having been knocked unconscious with the Guardians instantly putting up their guard.

Divine Aura: She attracts undead to her, shown during episode 12 when more skeletons gathered around her.

Water Manipulation: In Episode 3 of Season 2, she showed herself capable of controlling a flood of water and scattering it.

Magical Resistance: She is immune to Ainz's Time Stop ability and Despair Aura.

Kazuma Sato
The two have a strict platonic relationship. One with Kazuma calling her useless and Aqua seeing him as a jerk. Being mad that he calls her delusional to others about her Goddess status.

Darkness
Her ally and friend back from their world.

Megumin
Her ally and friend back in their world.

Ainz Ooal Gown
She dislikes Ainz and his group since they are undead and other such supernatural entities, constantly trying to purify him and refuses to listen to him. Her hatred of them would probably increase if she learned of the atrocities they committed back in their world. She also knows he is an Isekai person like Kazuma. As the series progresses, she shows some tolerance to him though can get offended - her opinion - when he talks back to her. She is one of the few that shows no fear toward him and his immense powers.

Albedo
She kind of gets along with Albedo, defending her for being a virgin. The two due bicker a lot, with Albedo calling her a harpy.

Tanya
Despite Aqua's claims of being a Goddess, Tanya didn't seem to notice up until she told her and the other three Isekai boys that she knew they were from earth. Aqua then becoming terrified at Tanya's rage toward her and was fearful being lucky when Subaru and Ainz calmed her down. Tanya apologizing with Aqua fearfully accepting yet also still upset she doesn't believe her as a Goddess.

Tanya has however stated she wouldn't mind helping her in classes-Aqua refused though. And was upset when she saw Aqua cheating. She also aided with Megumin's plan in getting her, Kazuma, and her Aerial Troops out of detention.

Subaru
She recognized Subaru as a Isekai person. He would help her out when Tanya would put her rage against her. He doesn't believe she is a goddess. The two are part of the animal care group.

Chris
She like to tease Chris particularly about her small breasts.

Rem
Rem was able to get Aqua to help out with rebuilding the arch through kind pressure. Capable of holding back from attacking Aqua and was nice to her even though Aqua refused a lot but obeyed anyway.

Death Knight
She has tried to exorcize Death Knight before.

Trivia

 * She is able to deduce Ainz, Subaru and Tanya are from earth, due to having sent people like Kazuma Sato to other worlds before. She is the first to realize that all 4 groups have an Isekai character.
 * She is one of the few to actually hurt Ainz much to everyone's surprise.