a simple explanation is it is a trope with an esper and a guide. One character has magical powers (esper), but the con is to maintain their magical powers and sanity, they need to receive "guiding" (from the guide) which most of the time the form is intimate physical contact. There's more into this I think but this is just the basics coz I dont normally read this kind of trope.
you can search for guideverse tag here or maybe others will comment guideverse recos coz like I said i dont normally read it. It just so happen that the guideverse side story AU is really good!
Im really holding on to this because Im waiting patiently for the guideverse AU (chapter 73-90) I dont understand korean but it is the best AU side story for me imo that it could be a separate story.