This Is Screwed Up, but I Was Reincarnated as a GIRL in Another World! (Manga) Vol. 4

Ren is thriving in another world, thanks both to her broken magic skills and the scientific knowledge from her past life as a middle-aged scientist. She's completing quests, perfecting her cooking skills, and getting very close to a pair of gorgeous sisters! But when she unwillingly reunites with Neil, who knows nothing of Ren's prior existence as a cranky old man, life suddenly gets very difficult. To escape, Ren sets off on a journey, which may well become the most challenging quest the new world has to offer!