Sex Life with Monster Girls ~In the Case of Alraune~

The protagonist, who overcomes the grief of losing his lover and lives each day with a positive attitude.
During his routine visit to the grave, he discovers a strange phenomenon—
Among the blooming flowers in the cemetery, there is one large bud that remains tightly closed.
Thinking of the flower bed planted for his lover, the protagonist can't bear to see it stay in bud alone,
So he waters the bud with the intention of "making it bloom."
The next day, while visiting the grave, an even stranger sight appears—
Where the bud once was, there now protrudes... a girl's neck!
Before the protagonist, whose legs have gone weak with fear, the head topped with a flower bud smiles sweetly,
And even speaks, calling him "Daddy."
She claims to be a monster named "Arachne" born from the aura of his lover,
And indeed, her appearance is exactly like that of his deceased lover.
But why does she call him Daddy? The girl explains with the natural, plant-like way of thinking:
"Since I was born from Daddy's lover's body, of course I'm Daddy's daughter."
This plausible-sounding yet absurd logic makes the protagonist laugh and cry,
But the warmth of being called father by a monster moves him.
Through a twist of fate, the protagonist names her "Aruru,"
And decides to raise this strange daughter as her father.
He thought it would be as easy as growing a potted plant,
But she combines plant characteristics with human habits, leaving him in a fluster.
The most troublesome is her "nutritional needs"—
Besides normal food, she must regularly absorb human vitality,
Otherwise she will wither and fade away.
Unable to bear watching the daughter who calls him father disappear,
The protagonist begins to regularly supply his own vitality to her.
A human father and a monster daughter, this bond that began by chance,
What kind of connection will it ultimately nurture...?