Similar to the "Harpie" monsters, the "Lyrilusc" monsters consist of female monsters with bird features. They appear to wear a full-body costume based on the birds of their namesake. The Main Deck monsters have a child-like appearance, while the Extra Deck monsters have an adult-like appearance.
Its name in the OCG reference, Luscinia, is a genus of smallish passerine birds, but each of them belongs to different families of this genus. The base character used for its Japanese name "Lyrical Luscinia" ("LL") is similar to the one used for "Raidraptor" ("RR"), reflecting that these archetypes are used by the Obsidian siblings.
The names for each Main Deck member contain both a blue mineral/gemstone and a passerine. The former may a reference to the fact that Lulu's Japanese name, Ruri, means "lapis lazuli".
The "Lyrilusc" archetype consists of Level 1 monsters focused on Rank 1 Xyz Summon tactics. They possess swarming and searching effects to aid quickly Summoning their Xyz Monster, "Lyrilusc - Assembled Nightingale", whose ATK and number of direct attacks quickly increase with the more monsters the player manages to gather to Summon it. With enough Xyz Materials, "Assembled Nightingale" can quickly OTK your opponent without much problem. Otherwise, it can be used as Fusion Material for "Lyrilusc - Independent Nightingale", whose ATK and burn effect can also become massive depending on the number of Xyz Materials attached to the fused monsters.
Despite their ability to quickly bring out their main powerhouse and massive protection against battle, targeting, and effect destruction, cards that can negate their effect or flip them face down such as Skill Drain or Swords of Concealing Light will shut them down.