The successor, Umajirushi DC Chalk, is available here from JetPens (San Jose, USA), $1.80 for 6 sticks, or 30¢ per stick (also available in a 72 pack like shown in the video)

https://www.jetpens.com/Umajirushi-DC-Chalk/ct/3774

“The two well-established chalk makers Umajirushi and Hagoromo worked together to develop this chalk.”

Thinking a six-pack might make a nice no-reason gift, to friends’ kids or my local baker or church who uses a chalkboard, I just placed an order.