It is an AR game using GoogleARCore and GPS. It has been upgraded to 4.0.
You can place the captured vengeful spirits wherever you like as earthbound spirits.
Place them in your room, at work, or at a friend's house to nurture your earthbound spirits.
Please check the FAQs for details on version upgrades.

It's very easy to use. When the app detects a sign, scan it. If the vengeful spirit is found, it will appear and the nine letters will be cut. If your Virtue is high, you can catch it relatively easily, but if your Virtue is low, even if you are using Hoichi's tag, which is difficult for vengeful spirits to find, it will be noticed and escaped.

Virtue can be accumulated by healing the grudges of ghosts with the "Soul Sleep Pot" that you have if you catch them, but it will be lost by placing the captured ghosts as earthbound spirits.