Below is a walkthrough of the Runic Disruption main story event in Rune Factory 5.
Client: Livia
Location: Belpha Ruins (Recommended Level: 5)
Objective: Investigate the Belpha Ruins
Belpha Ruins B1
As part of the main story, Livia will tell your character to report to her office first thing in the morning. Doing so leads to a dialog event where you’ll be tasked with investigating the Belpha Ruins. When it ends, exit the Silo and head for the southcentral part of town towards the marker to arrive at the Belpha Ruins. Head inside the building and use the save point then follow the stairs down to officially enter the ruins. For this party, just follow the path dealing with the goblins along the way. Eventually, you get trapped in a room with some goblins. After you defeat them, there will be a small side room containing a chest. Grab the chest then head to the next room. Here you’ll have to run up a hallway while avoiding the giant rocks that roll down the middle. At the other end, there will be a chest next to the path to floor B2.
Belpha Ruins B2
Follow the path until you reach a room with some big bugs. Defeat them then activate the switch on the northwestern side of the room to cause the wall to drop. Continue following the path to reach the center of the floor. It consists of a narrow circular hallway with four small areas in each corner and the way forward in the northern part of the area. The way out is blocked by three walls that you’ll need to lower. You’ll also want to watch out for a rock ball that circles the hallway. In the northeastern area, you’ll find two chests, some ghost and fish enemies along with the pink switch. The southeastern area contains a single chest with the yellow switch and you can find the blue switch in the northeastern corner. It’s protected by a group of ghosts and there is also a chest there. After pressing all three switches, head north of the circular room to find the way to floor B3.
Belpha Ruins B3
Make sure to save and heal up if needed then proceed to the center of the room to trigger a dialog event. This will lead to a boss battle with the monster Cerberus. It uses lunge and swipe attacks with a magical ball thrown in. When its health gets low, it enrages and will start jumping up into the air. It also has a feint move where it pretends to be dead, but you can still hit it. When the monster is defeated, fast travel back to the Silo and report to Livia for a dialog event. The event completes after you go to sleep.