Only a few people with special abilities like Tanda and Asra can see Talhamaya. Its form is vaguely described as having fangs and scales. Talhamaya likes the taste of blood and is inclined to kill people and animals.
Talhamaya appears in this world during a spring season in Noyook that usually spans about a hundred years. During that time, an invisible holy river flows from Noyook to this world, that makes climate warmer and improves conditions for farming and herding. However, it is the streams of that holy river where Talhamaya lives.
There is a wooden ring located in Noyook that can become a portal that allows for Talhamaya to get to real world. Once a female member of Tal tribe, who can actually see the ring (which is an extremely rare ability), contracts the ring into her own body, she becomes able to call Talhamaya to this world at will.
That woman can eventually fully merge with Talhamaya, becoming Sada Talhamaya. In that case, she becomes immortal and ever-young until the end of Noyook spring.
Several hundred years before the events of the novels, previous Sada Talhamaya had united Rota country (then called Rotalgal) and ruled it as a bloody dictator. When her powers began to wane, a young Rota warrior called Kiran (キーラン), supported by Kashals and some Tal priests, killed Sada Talhamaya and established the Kingdom of Rota, becoming its first king.