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 the Slime girls. 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.

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 seem to be dominant in arguments with her daughter as Suu seems more embarrassed than intimidated 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.

Pysical 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, this 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 thelepathic connection to her Slimes, as Nega-Suu tried to transmit her knowledge and skills to her mother.
 * Weaknesses: Similar to a Yuki-onna, an Undine can temporarily lose control of her elemental abilities if she gets emotional. When Nega-Suu communicated with her mother, she was so afraid that she lost her concentration, causing the water in the "Lazy Pool" to foam and create waves and a large current.

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 household girls who is not of the same Liminal species as her daughter.