Two Realms: Hogwarts' Clock Tower Magician

On September 1, 1991, Hogwarts welcomed a group of new students. Among them is the famous Harry Potter, and also comes with an inconspicuous magician from another world. He is Plutarch Mestrius, a time-traveler who is determined to stay the course and never stand out. Many years later, Kuroyukihime's good senior brother, the fiancé of Lord Bartholomew, the best friend of Lord El-Melloi II, the godfather of the magical girl Illya, the adopted brother and adopted father of the savior Harry Potter, the Minister of Magic of Great Britain, the new principal of Hogwarts, and the crowned magician Plutarch Mestrius, delivered his inaugural speech in the Great Hall of Hogwarts. "Welcome to Hogwarts. Just a few words. "Idiot! Cry! Residue! Screw! "Thank you everyone!" The audience burst into applause. PS: [The timelines of both sides are synchronized, and the Holy Grail War takes place in January 1994. [The protagonist will fight the Holy Grail War, and the servant will create two Caster rituals. After all, Sister Shi has some overflowing combat power in both the killing and sword levels. [The heroines are Lord Barthemero Lorelei and Kurogiri Hana. All other official CPs will not be dismantled.