BY　ballpoint pen

This is an original ballpoint pen with a body made of "Pt7" from Mitsubishi Pencil's new brand "3&bc". It features specifications that allow it to be used in water and zero gravity.

What is Pt7?
https://www.mpuni.co.jp/special/3andbc/index.html (Japanese)

Ball size : 0.7mm
Ink Color : Black
Made in Japan