It turned out the other day that another supermarket named Y'smart sells the chilled cup of TRIPLESSO!
If you wonder what the TRIPLESSO is, please check this past article.
Now there are four channels you can buy TRIPLESSO as of December 14, 2017. By the way it also turned out through Twitter that TRIPLESSO is not that easy to buy in rural areas. There seems to be only buying a box of TRIPLESSO through Rakuten online for those in rural areas. I hope we get more information other than from Tokyo Metropolitan Area...
SANWA, Summit Store, Don Quijote, Y'smart
Seven Eleven, Familymart, Lawson, Seiyu, My Bascket, BIG YOSUN, Ito-Yokado, AEON, Inageya, Maruetsu, Shokuhinkan Aoba, Seijo Ishii, The Garden