Only after hearing the Third Hokage's words did Shin Uchiha realize he had taken too much for granted. He had assumed that however willful Tsunade was, she would still listen to her teacher, the Third Hokage. Instead, his plan had failed at the very first step. If he couldn't even get her to come back, what else could he do?
Shin Uchiha frowned deeply, silently wondering whether there was another way.
In the original story, Tsunade had only returned because the Third Hokage was already dead, leaving Konoha without a Hokage. She hadn't wanted her grandfather's life's work to go to waste. Combined with Jiraiya coming to find her, Orochimaru's unwitting assistance, and Naruto's persuasive speeches, all those factors had finally brought her back.
Now, however, the Third Hokage was still alive. There was actually some estrangement between him and Tsunade, which was why she hadn't returned. Jiraiya wouldn't lie to her and say the Third Hokage was dead, either, so getting Tsunade to return to Konoha really wasn't very likely.
Shin Uchiha sighed in frustration. He had originally planned to see Shisui, Itachi, and the others off in a few days, then head to Iwagakure to have some fun with the Tsuchikage. While he was there, he would copy the man's signature Light-Weight Rock Technique and his kekkei tōta, Dust Release, to shore up his own weaknesses. (After his Mangekyō Sharingan evolved into the Eternal Mangekyō Sharingan, his Copying Eye could already copy kekkei tōta.)
After all, flying freely through the sky had always been humanity's dream. In the shinobi world, aside from reaching the Six Paths level and gaining the ability to escape gravity and fly freely, there were only a handful of other methods.
There was Sasuke Uchiha's method: finding a summoning beast that could carry him