Lilith & Lilim

Powerful succubi who were defeated by Heinrich 500 years ago, Lilith & Lilim are twins who were entrusted by Black Alice to lead their race to a haven. Lilith is the taller sister with a flat chest, and Lilim is the big-boobed younger one.

The Succubus Witch attempted to revive them during this year's Purple Sabbath, only to be stopped by Luka. However, she manages to transfer her power to Lilith & Lilim before she is sealed.

The two demon twins arise and take notice of Luka. They are shocked that he is the current wielder of the Angel Halo, the "accursed sword" that sealed them 500 years ago. They mention that he looks and smells like Heinrich, and Luka possesses the same power as him when he uses Gnome to shove them off.

After Luka reseals them, Alice soon steps in and accidentally unseals all the succubi when she tries to revive the fallen men. Lilith & Lilim take note of the Monster Lord and assume she's Alice the XI (Eleventh), but corrects them. The succubi then explain that Lilith & Lilim were the ones to lead the succubi to a haven without being orchistrated (as human females dislike them for some reason). The men rush in, touched by their dreams, and decide to coexist as "succubi and male livestock" to be milked endlessly.

Encyclopedia Entry
"Legendary Succubus Sisters that were sealed 500 years ago by a Hero. Incredibly strong Succubi, they are treated by other Succubi as their savior.

''Top-class Succubi, they work together to indulge a man in ecstasy. Entangling their bodies together with the man's, they take turns mating with him all while rubbing their bodies against his.''

''To tell them apart, the other sister with smaller breasts is Lilith, and the younger sister with larger breasts is Lilim. The two consider themselves of the same flesh, and cannot bear to part with the other for longer than a few moments."''

Battle Overview
Being the leader of the succubi, Lilith & Lilim can be very troublesome. There are two of them, which means double the damage. Additionally, she also can steal Luka's HP or SP. Using Gnome helps stave off damage while Sylph is useful for preventing HP/SP loss.

The offensive relies on using Lightning Sword Flash to dish out the most damage, but Meditation can come in-handy in times.

If they mount Luka, Struggle with Gnome up is necessary or they will proceed to rape him with Hold Drain and Energy Drain which leads to a KO. Additionally, if they manage to steal SP with Twin Energy Drain, Guard right after to withstand their Chaos Pleasure.

If Luka succumbs to rape, they take turns with vaginal intercourse and does anal with their tails, then keeps him as a sex slave.

Trivia

 * The two do not mention Heinrich's name explicitly, merely referring him as a "disgusting hero". Having being defeated 500 years ago and Luka possessing the "same power as that disgusting hero", the "hero" is no doubt Heinrich.
 * Technically they are the "true" queens of succubi for leading their own race, unlike Alma Elma who simply doesn't care about them.
 * They're the only one-time appearance boss in the game which manages to actually contribute to the overall plot, revealing Luka's relation to Heinrich as well as making note that the Angel Halo belonged to Heinrich at one point.