Shin and the others left the Land of Water, but instead of returning to Konoha, they went back to the Land of Whirlpools.
They built a simple little house by the coast of the Land of Whirlpools.
Kushina and Mikoto sparred on the beach, hoping to gain practical combat experience.
But it wasn't very effective. Their match was only a friendly spar, so they certainly wouldn't use any dangerous ninjutsu, let alone fight to the death. It didn't do them much good.
Shin sat by the sea, preparing to develop ninjutsu.
The ninjutsu he wanted to develop was Ice Release. Although he had acquired the Kekkei Genkai, he didn't know a single Ice Release technique.
The fundamentals of ninjutsu filtered through Shin's mind again and again. At the same time, he recalled the ice-based abilities he had learned about in his previous life.
Those abilities offered Shin plenty of inspiration. Perhaps, after studying them, he could develop them in the form of ninjutsu.
There were many ice-based abilities. For example, there was the user of the Chilly-Chilly Fruit in One Piece, Aokiji, one of the Three Admirals.
There was Esdeath, the Ice Queen who wielded the Teigu: Demon's Extract. She could even freeze time with Mahapadma.
There were the ice mages in D.N.Angel, Hyoga's techniques in Saint Seiya, Toshiro Hitsugaya's techniques in Bleach, and so on.
There really were quite a lot of ice-based techniques, and many of them were powerful. But developing them was no easy task.
After thinking it over for a long time, Shin decided that recreating techniques from other worlds through ninjutsu wasn't something he could accomplish overnight.
"So I can only create Ice Release techniques based on other ninjutsu..."
Shin sighed. He knew he would have to put a lot of effort into Ice Release.