Complex sentence: After Persia called Ran to join the newly formed third generation of Weiss, as a constant reminder of the purpose behind his actions, Ran takes on his sister's name and wears one of her earrings, which were actually a gift from him to her.
Split into simpler sentences: After Persia called Ran to join the newly formed third generation of Weiss, as a constant reminder of the purpose behind his actions, Ran takes on his sister's name. He also wears one of her earrings, which were actually a gift from him to her.