What is Suriage in Japanese Katana terminology?

The term "Suriage / Suriage Nakago" (磨上げ／摺上げ茎, すりあげ／すりあげなかご) refers to the process of shortening the blade of a Japanese sword by cutting off the tang end (Nakagojiri) and grinding it down. This process is often carried out in conjunction with "Machiokuri" (区送り), which involves reducing the upper part of the blade section (Kamimune) and the edge section (Hamachi). This results in a shorter blade, but the tang remains untrimmed, thus it is still considered a "Ubu Nakago" (生ぶ茎), or original tang. This process is typically carried out to adapt the sword to changes in fighting styles or to repair damaged or broken swords.