>>58409878Sirenmon is the right hand of bacchusmon, the chief of the village of the Gear Forest, he's constantly partying and getting drunk, forcing Sirenmon to take all the choices of the village and be the serious one of the relationship, she gets the shit done and respects Bacchusmon, she also has a beautiful song and Bacchusmon loves to hear her sing, it's the only thing that gets him happy, however during the war against the titans, Bacchusmon is asleep while the titans kill and murder everyone on the village, he gets to see Sirenmon die next to him, he avenges her and buries her body onto the ground.
During the decisive fight, Sirenmon's body reemerges as a giant undead grass and rocks bird called Ceresmon, the human posted on that meme is her human form that controls the giant bird.