Complex sentence: A Demon King named Arawn was sealed away for 1,000 years and when a girl named Riannon releases him, they travel together and become emotionally attached to him.
Split into simpler sentences: A Demon King named Arawn was sealed away for 1,000 years. After a girl named Rhiannon (Ri-a-n-no-n) releases him, they travel together and she becomes emotionally attached to him.