You've came to a place of nothingness.
I'm not even sure how you even managed to get here in the first place but as a reward of your boldness you get to know about the forbiddens.4 sisters forgotten in time, whose power shall not be spoken of. I still will tell about it to you.

Mana...The youngest of the 4 sisters and yet she shouldn't be overlooked.
Her method of attack is quite... Brutal... She attacks her opponent until they are weakened enough. When her opponent is weakened enough, she can absorb their soul.Appart from her property to absorb the soul of anyone weak enough, she can also extend her arms and legs to unknown extends.
Another thing that she can do is use the power of the souls she absorbs to make herself stronger.She's oftenly cold and stubborn at times but other than that don't attack that often unless she senses that you're a threat or that she's in dire need to consume a soul.Some might say that she has an inferiority complex about her sisters.

Vita...The second younger of the sisters, someone that seems constantly tired. Her soul taking methods are like her personnality. She takes the souls of the ones who are too tired.How does she make someone tired ? Simple everyone meeting her eyes for too long will get hypnotized and will eventually sleep.But other than that she's very unlikely to attack you. She's too tired to engage into a fight and it's mostly her sisters that gets her the souls she need to live. But despise that she is also a danger among these sisters.

Endu...The most peaceful one, always kind about others, even to strangers. Funnily enough her fighting methods are one of the mostal brutal of the sisters. Upon meeting her gaze you will slowly vanish, turning into dust leaving only your soul that she can harvest.She's old enough to be among the "black hair". The black hair are the elites amongst the sisters, the strongest. That gives her surhuman abilities, endurance reaching incredible limits. Black hairs are threats that you should avoid at all cost.Hopefully, this one rarely attack, she's only here to hunt when she needs it.

Sta...Th strongest of the sisters, the oldest of the sisters, the most aggressive of the sisters.Her methods of killing are also straightforward, she inserts her opponent in her mouth, turning them into mashed meat only to spit out the soul, ready to harvest.Other than that ? She's a tall menace, able to easily lift trucks and can mimic a bit of her sisters' ability.She's dangerous and she's the most hostile of the 4. Do not bother her or her sisters if you care about life.