Suu's Mother

Suu's Mother is a female Undine, who is more or less the Mother of Suu and Nega-Suu since she created Suu but the latter only becomes hers after absorbing the former's essence. She makes her debut in Chapter 67, although in that chapter she only has a minor role as one of Yukio's friends, before being officially introduced later in Chapter 81 along with her relationship with Suu.

She is currently in a business relationship with Mr President, including being instrumental in the construction of the Black Lily Waterpark.

Appearance
Suu's mother is a buxom woman with large breasts and even wider hips. As an Undine she has long, tentacle-like hair that reaches from her back to her feet. In general appearance, she is more or less not dissimilar to a Slime overall, with the exception of her crisp human-like skin.

For her debut at the Arctic Inn, she wore a long-sleeved figure-hugging dress with a mandarin collar that leaves the shoulders exposed as well as a pair of shoes. In Chapter 81, she wears a onepiece suit of similar design with long sleeves that tapers off from the waist down between the cleavage of her butt which leaves her buttocks naked. She also wears long, dark pantyhose that completely cover her feet. During her stay at the Black Lily Waterpark, she also wears a kind of sombrero on her head, which, however, is apparently just a replica made of water and foam and not a real hat.

Personality
Suu's mother is a very kind and polite person. As it can be seen in Chapter 67, she is very helpful when she actively supports Yukio in temporarily transform the entire bathhouse of the Arctic Inn into a premium sauna together with the Salamander woman.

Suu's mother cares about her family. She considers her Slimes as to be her "daughters", although she admits that this relationship can be viewed as more or less. She's also willing to openly admit her mistakes and take responsibility for her daughters' mistakes, although she does point out when a mistake isn't entirely her fault, as seen in her conversation with Mr President. She expresses herself very eloquently and in detail.

While Suu's mother is very polite, she doesn't seem to have a good relationship with Suu. She is disappointed that despite the long time she has lived with Kimihito, Suu has not yet bred with him to reproduce, which is the real reason why she sent her daughter to Japan back then. This shows that Suu's mother has certain demands on her daughters but unlike Meroune's Mother, she doesn't always seem to be dominant in arguments with her daughter as Suu seems to be partly intimidated but also embarrassed by her. Suu's mother was taken by surprise when Suu covered her mouth, showing that she may not be used to her "daughters" contradicting her.

Personal Traits:

 * Possibly wealthy: When Suu's mother entered into a business relationship with Mr President, she told him that she would pay for the construction of the Water Park "whatever it cost", implying that she may be wealthy or financially independent.

Physical Traits

 * Undine Physiology:
 * Hydrokinesis: As elemental Liminals of water, Undines can control water at will or create it physically infinite. This allows Suu's Mother to reduce the water bill of the Black Lily Waterpark to zero, as it makes the park independent of any outside water source.
 * Walking on Water: As Suu's Mother shows in Chapter 81, Undines can walk on water without sinking.
 * Steam Generation: When a Undine's water abilities combine with a Salamander's fire abilities, they create a warm water vapor that can temporarily transform an entire bathhouse into a giant sauna as seen in Chapter 67.
 * Creating Slimes: Undines can create Slimes, making them the ancestors of the Slime species. However, the exact process by which Undines can do this is unknown, although Suu's Mother implies that this is not done through a biological reproduction, so a Slime can only be considered more or less as the child of the Undine who created it.
 * As Suu's mother explains to Kimihito and Mr President, an Undine seems to have some kind of telepathic connection to her Slimes, as Nega-Suu tried to transmit her knowledge and skills to her mother.

History
Not much is known about the past of Suu's mother, but she lives outside of Japan and seems to have been a good friend of Yukio for a long time. At some point before the events of the series, she created at least two Slime girls (one of whom was Suu) who she considered her family. Eventually, Suu's mother sent her "daughters" to Japan in order to create a place where they could live with their mother, although Suu's mother believed that in order to do so they should also have to reproduce to "increase their numbers". It is unknown how Suu's mother sent her daughters to Japan, but in both Chapter 9 and 10, Kimihito, Miia, Centorea and Ms Smith discussed that Suu may have immigrated illegally, so it is possible that Suu's mother smuggled their daughters into the country.

Sometime before Chapter 81, Suu's mother learned that Suu was living with Kimihito as a homestay girl, but she was disappointed that Suu had not yet bred with him despite the long time she had already lived under the same roof with Kimihito. This leads to an embarrassed Suu covering her mother's mouth to stop her from embarrassing her and pulling her away before things became any more awkward.

Helping Yukio at the Arctic Inn
Suu's mother makes her debut in the manga series in Chapter 67, but she doesn't play a major role in this chapter. At Yukio's request, Suu's mother and Yukio's Salamander friend visited the Arctic Inn, where the two combined their elemental water and fire powers to create steam that they used to transform the entire bathhouse into a giant sauna as a special service for the guests. Later, Suu's mother was seen in the ice bath created by Yukio and having a friendly conversation with a male human guest, while Yukio chatted with Kimihito and his homestay girls.

However, due to the minimal interaction between Suu's mother and the protagonists, they didn't learn about the Undine's connection to Suu at this point.

Business relations with Mr President and construction of the Black Lily Waterpark
Suu's mother eventually moved to Japan and contacted the Black Lily Laboratory because she wanted them to make a place for her as an Undine during her stay in Japan, since the Japanese Government doesn't care much about the individual needs of Elite Liminals. Suu's mother also assured Mr President that she would pay for this project whatever it would cost. Since Mr President was pleased with this proposal, they took a bit of their resort project that was already under construction and changed things around into a specialized clean pool fit for an Undine to utilize: the Black Lily Waterpark.

Suu's mother was instrumental in the construction of the water par because, as an Undine, she has the ability to create infinity water, which reduced the park's water bill to zero. Mr President also used a Slime girl for the water park's filtration system, although he didn't know that this Slime girl was the second daughter of Suu's mother.

Zoological Classification
Undines are a Liminal species of elemental spiritual beings associated with water. Also known as "water nymphs", Undines are usually found in forest pools and waterfalls and have beautiful singing voices.

Undines are considered one of four Liminal species that embody the cardinal elements; alongside the Sylph (Air), Salamanders (Fire), and Gnomes (Earth). Undines are revealed to be able to create Slimes which are a completely different species of Liminal girls but the method is still a mystery.

Trivia

 * Suu's mother is the only known mother of one of Kimihito's homestay girls who is not of the same Liminal species as her daughter.
 * She's also the first shown to be a grandmother.