Fallen Priestess: My Sister's Demonic Bloodine

The only way to stop my sister from turning into a succubus is to defeat the Demon Lord?!"
In the quaint town of Aslint, Lloyd embarks on a quest to defeat the Demon Lord to save his sister Trina from succumbing to her succubus blood. Join Lloyd on a classic adventure where he gains experience, conquers dungeons, and utilizes his unique Synthesis skills to protect his sister.
However...

"What's this? Who left this behind? Whose memory does this belong to?"
"Synthesis" is a powerful technique surpassing alchemy, taught to Lloyd by his master in the magical arts. It's invaluable in his adventures. Though typically used to locate items, Synthesis also allows Lloyd to experience the memories embedded in objects. Lately, he's been finding torn clothes and soaked strands of hair around town at night. Curious, he uses Synthesis on these objects, witnessing visions of a beautiful woman engaging in intimate acts with a stranger, her voice and expressions unlike anything he's seen before.
Whose memories are these? Will Lloyd continue to encounter such lewd and depraved visions every night in Aslint?

Balance your day and night activities, managing both your stamina and mana. How will you satisfy your sister tonight?
As Trina's succubus instincts grow stronger, she requires a regular supply of mana in the form of a man's life energy. Should you focus on conquering dungeons to find a cure for her transformation, or will you use your limited stamina to quell her insatiable desires?
No matter your choice, Trina, your understanding sister, will support you. However, if you're not around, her succubus instincts might take over, leading to unexpected events during the night in Aslint.

"Brother... Trina has been doing her best... So, if it's just a little bit... it should be fine, right?"
As night falls, Trina's cravings intensify. Unbeknownst to Lloyd, his timid sister is slowly transforming into someone he barely recognizes. As her brother, can he stop her transformation before time runs out?
Your choices will determine if their sibling bond is restored or forever altered by the end of their journey.