A half-phantom could be said to be half-alive and half-dead at the same time. Because Youmu has no desire for either life or death, Miko could not read Youmu's desire with her ability. That made Miko mistake Youmu for a hermit, even though Youmu is just a half-human half-phantom...

The big white comma floating around Youmu is a half-phantom. At the same time, it is also Youmu herself. It helps out in battles of bullets and is apparently slightly bigger and warmer than a regular phantom.

Youmu is said to dislike ranged battles, but she makes up for it by moving in sync with the half-phantom part of her and using flying slash attacks. This gives Youmu an unparalleled strength at both short and long range―not much gets past her.

Youmu's Spell Card shows how strong she can be when her half-human and half-phantom parts work together. In Soul Sign: Wheel of Pain of the Living and Dead, her phantom half turns into a copy of her human half and attacks.

Because half of Youmu is a phantom, her lifespan is longer than that of a normal human. Her grandfather, Youki, saw the Saigyou Ayakashi in full bloom, which means that he lived for at least one thousand years. Perhaps Youmu will be able to see the Saigyou Ayakashi blossom one day too.