Hamefura - Otome Game no Heroine o Sankai Ikasenaito Hametsu suru Heya ni Haitte Shimatta... (Doujinshi)

Bonus manga from Kon's BOOTH page.

"When Lady Katarina looks at me like that..." One of the Seven Wonders of the school is a book of erotic magic named “The Story of Desire“. Previously, Katarina and Maria got trapped inside that book, but the only way to escape is to bring Maria to climax three times!? The "Villainess“ Katarina was passive throughout the first story, as she had little knowledge of sexual activity. The "Heroine“ Maria was active in a sexual sense, and she taught Katarina plenty of sexual knowledge. Top and bottom reversed! It's Katarina's turn to use the knowledge she's learned! Here's a new high in sugar content! The sexual acts of Maria and Katarina opens with a reversal of their situation! (Source: DLsite)

"Three times? Lady Katarina, it's absolutely my fault." One of the Seven Wonders of the school is a book of erotic magic named "The Story of Desire". Nobody disposed of the book securely, so an incident happened! The "Heroine" Maria & the "Villainess" Katarina were both transported into the book of magic! The desire that they must fulfill to leave is to bring Maria to climax three times!? The "Villainess" is passive throughout the story, and the "Heroine" is active throughout the story. The erotic and love-filled comedy of love between two women is about to begin! (Source: DLsite)