The Earl's Daughter Has an Unwavering Otaku Soul (♂)

A modern-day Japanese company employee (28 years old, male, robot otaku) wakes up to find himself transformed into a beautiful black-haired young girl in another world. And that world was a fantasy realm with swords, magic, royalty and nobility, where monsters and spirits also lived. Wait, this has to be a lie? Bewildered, he faints, despairs... Without understanding what's happening, he drifts along with his surroundings for 15 years. Then on the day of the coming-of-age ceremony, a sudden change occurs to her (him)—!?