While "Silen" lacks direct references in available records, a demon named Sirène (alternately spelled "Sirene") features in the OVA as part of the central group. Portrayed as a female demon, Sirène declares a romantic bond with protagonist Akira Fudo, positioning herself as his lover and sparking friction within the group—particularly with Miki Makimura. Dr. Hell kidnaps Sirène in an attempt to coerce her into marriage, heightening hostilities between opposing factions.

She functions as a narrative foil, contrasting the chibi world’s moral ambiguity with the grim undertones of the characters’ native realities. Her involvement in a love triangle with Akira, Miki, and Ryo Asuka further strains group cohesion. While her exaggerated traits, amplified by the Super-Deformed art style, inject humor, her decisions critically impact major plot developments—including Dr. Hell’s machinations and the climactic clash with Satan.

Details about her origins, background, or evolution remain undocumented beyond her OVA-centric role. She has not been referenced in other official works, spin-offs, or adaptations within Go Nagai’s universe. Should "Silen" prove an alternate designation for Sirène/Sirene, these descriptions hold. Otherwise, no confirmed data exists for a "Silen" within the provided material.