Sadeena, formerly known as Nadia, is a Sakamata therianthrope and companion of the Shield Hero. She's also one of the top fighters of Lurolona Village. In her human form, she appears with long black hair, blue eyes and fair skin with black body lines running along her body and arms due to her orca killer whale pigmentation, and her height is average. In her Sakamata form she has the appearance of a therianthrope Orca, Sadeena is quite large in human standards when she is in her Orca form but average-sized for her Orca race. She also tends to wear a loincloth. Raphtalia, Filo, villagers in Rock Valley, and the people in the other village hold great respect for her, although Naofumi can only see her as a loose person who likes to play around and drink alcohol. Sadeena was born and grew up in Q'ten Lo islands in a special lineage related to the God Water Dragon Devotion.

Sadeena was born and grew up in Q'ten Lo islands in a special lineage related to the devotion of the God Water Dragon and the Heavenly Emperor. At some point in her adolescence, she became the head priestess of the Water Dragon and became friends with the heir of Q'ten Lo throne, Raphtalia's father. After that, under unknown circumstances, she decided to follow Raphtalia's parents when they decided to elope from the country, leaving behind her old life.

After leaving their country, she and Raphtalia's parents settled down in Melromarc's Seaetto territory, as the governor was receiving great quantities of immigrants as part of the Queen's initiative to create a Demi-human protected district. Once, she rescued Keel from drowning in the ocean.

Sadeena went far away for fishing, during the events of the first wave, and was unable to return in time to rescue the villagers. Raphtalia and the surviving villagers believe that the catastrophe of the wave and it's monsters could have been subsumed if Sadeena was present. Sadeena herself regrets not being there in the village when it was under attack from the wave's hazards.

Sadina can also fight both in close quarters and with magic using her Vassal Harpoon. She can also use a wide range of ritual magic including self-buffing magic as well as Choral Magic. Though slower than Raphtalia, she runs at a speed greater than that befitting her level. Elrasla Ragnarok said that she was one who could master fighting by instinct so there was no real need to learn Hengen Musou anyway. She can use lightning magic on herself to forcefully increase her own reaction speed to levels equal to the Hengen Musou skill Musou Kassei. She can use echolocation to read movements, so illusion magic isn't very effective on her.

Sadeena's magical abilities are:

Saint Aquabolt: Unleashes a shining mass of water.

Faust Aquashot:

Enraged Dragon's Twin Blades:

Reverse Prong Attack:

Thunder Impaler:

Saint Aqua Shield:

Draifach Thunderbolt: The clouds in the sky begin to grow dark, and lightning flashes between them. The clouds gather around her outstretched Vassal Harpoon.

Dreifach Chain Lightning: From the tip of Sadina's harpoon, several streams of lightning bright enough to cause permanent eye damage.

Water and Lightning Fusion: Pre-prepared Choral Magic.