Betrayed by his friend and died accidentally while escaping.
Reborn as a mermaid, living in the future world,
Because he was stunned for a moment, he was regarded as mentally retarded.
Looking for true love in the name of being mentally retarded,
Live your life with the voice of a mermaid.
I'm a newbie, so please bear with me.
Protagonist's personality: sometimes a fashionable novice, sometimes a scheming villain, sometimes off-kilter