What is the strongest katana made of?

I'm curious to know, what material is used to craft the strongest katana known to exist? Is it the traditional Japanese steel, or has modern technology introduced new alloys that can enhance the strength and durability of these legendary swords? Surely, the answer lies in the intricate craftsmanship and the meticulous selection of materials that have been passed down through generations of skilled swordsmiths. So, what is the secret to creating the strongest katana?