Avalon no Nazo, the sequel of Tears to Tiara takes place right after the defeat of the Erin and Albion kingdoms. The two new kings in Avalon city are planning a carnival to celebrate the end of strife and that peace has finally came.

Busy with preparations, people have missed the signs of unrest in the air. When Arawn, the demon king woke up to find his room covered in strange vines, it was too late, the whole city has started mutating.

[From Play-Asia]