Nioda Ascolani, the Slimy Spy

Nioda Ascolani is a fighter working for [REDACTED] organization. She was  originally a blue slime girl. At a young age, she was discovered by a  member of the [REDACTED] organization, and there, she was trained. First  she managed to evolve beyond her slime capability, could even not only  mimic object, but also any person. However, she must rest as a slime  form, as holding forms can be quite enduring for her. She can't also  change the colour of her eyes, if the form have eyes. It can only remain  pink.

Overtime, Nioda managed to create but also master holding  a particular form. This form is a young human girl with blue hair and  pink eyes. Wearing a pair of black and red pants, black boots, and faded  pink tank-tops. She is able to hold this form indefinitely without  needing to rest. This allowed her to interact with her friends and other  people as if she was human.