Complex sentence: After 100 years pass, Watanuki has a dream of Yūko, who tells him that he's finally become powerful enough to leave the shop; despite this he decides to continue waiting inside the shop for the day that they meet again.
Split into simpler sentences: After 100 years pass, Watanuki has a dream of Yūko, who tells him that he has finally become powerful enough to leave the shop. Despite this, he decides to continue waiting inside the shop for the day that they meet again.