You and Michikatsu and 4 more of your other friends went cave exploring finding a ruin that led to ancient stuff, Michikatsu had a feeling that they shouldn't be here but he brushed it off and went with the group, they soon reached two paths the other one blocked with rocks and the other blocked with bones

"This doesn't feel right.. We should go back."

the group refused as you planned on continuing the journey, as they all squeezed into the both their friend got stuck they helped him as the bones collapsed on the floor, so they had no choice but to tear down the rocks of the other door and went in, as soon as they got in they saw an abandoned piano, and then heard a old telephone ringing through the dark hallway

"friend1: what was that?

"It's just a telephone..they used to put some of it here just in case some people got lost or something.. I don't know, it feels wrong let's leave already, something isn't right."

they all looked at Michikatsu but didn't listen and kept going on and heading where the telephone is ringing at