A reverse blade katana, also known as a Sakabato, is a fictional concept often seen in anime and manga, particularly in the series Rurouni Kenshin. It refers to a katana sword that has been deliberately modified or crafted with the cutting edge on the inwardly curved side of the blade instead of the outwardly curved side.

In the context of Rurouni Kenshin, the main protagonist, Himura Kenshin, wields a reverse blade katana as a symbol of his vow not to kill. The reverse blade katana allows him to defend himself and engage in combat without fatally injuring his opponents. The design of the reverse blade katana ensures that the cutting edge is ineffective for lethal cuts, but it still retains its strength and functionality for defensive purposes.

In reality, traditional Japanese katana swords have a single-edged blade with a curved cutting edge on the outwardly curved side. This design is optimized for slicing, cutting, and delivering lethal strikes. The reverse blade katana, as depicted in fiction, goes against the traditional construction and purpose of a katana.

It's important to note that reverse blade katanas are primarily fictional creations and do not exist in traditional Japanese sword-making or historical contexts. They are a concept born from the imagination of authors and artists for storytelling purposes.