They have a docile, quiet personality which is rare for a monster. Those who behold their appearance are somehow given an ephemeral impression. They are "shrine maidens" who serve monsters known as “ryu” who are worshiped as gods of water by some humans. They also have powerful water magic within themselves. They’re often the targets of faith, along with “ryu.”
As is typical with monsters of the Zipangu region, when a human man strikes their fancy, they fall completely in love, becoming so devoted as to offer up their very body and soul. Due to this nature, they never attempt to forcibly rape men. However, they never give up on a man once they’ve fallen in love either. No matter where the man runs to, they’ll chase him to the ends of the earth.
She’ll continue to shower him with love and devotion until he does desire to become joined with her. In most cases, they are so persistent that a man can never escape. Eventually, he surely becomes charmed by the love and demonic energy that he’s continually showered with. He’ll end up wanting to have sex with her and become a couple.
Her appearance, which gives off an ephemeral feeling as if swaying like water, gives the man the urge to spontaneously embrace her in his arms. And if the man draws her body near to him in that manner, she'll smoothly and quietly wind her snake body around his body in a way that feels like quietly sinking into water. During sex she receives all the man's heat and rage as if gently loving him with her body and heart, and the man will experience pleasure along with comfort, becoming engrossed with her.
Also, they have an extremely jealous side. They hate it when their husband comes into contact with another woman. If their husband is meeting in secret with a human woman or another monster, or cheating on them, then they become consumed with jealousy. After bearing through the anger peacefully, they seek to pour their mass of demonic energy into their husband. In contradiction to their watery nature, the mass of demonic energy born from their jealousy appears almost like raging flames.
Once implanted in the man’s body, the flames of jealously ignite his body and soul from the inside, causing him to be overwhelmed with a maddening lust for her body. The urges brought on by the raging flames within the man cannot be satisfied by any female but her.
Only by being wrapped in her snake body filled with the power of water magic, and mating, they will subside. During this time they freely exhibit themselves in a manner true to their nature as monsters that is so lascivious and entrancing that it would be unimaginable to those only familiar with their ordinary form. With the crushing weight of love and pleasure, she thoroughly instills her husband with the notion that she herself is the best female for him, and that he doesn’t need any other woman but her. The sex on this occasion gives the man pleasure and ecstasy incomparable to anything he could ever experience normally. It makes him become dependent on her as a prisoner of her body.
And even after that, the flames never completely disappear. They continue to smolder within the man. She is the “water” he must soak in, and he ends up being unable to calm down without having his whole body wrapped in hers, continuing to mate.
- Despite their jealous natures shirohebi can become part of a harem and one way or another get along with them. However they will make every effort to become the dominant wife and get the most sex. Things can get quite rough for the husband's body as the harem gets very busy until things are settled (source: Kenkou’s Japanese Q and A).