Lotteria Co. will launch a new version Friday of its smash-hit cheeseburger to stake a bigger claim to the premium burger market.

The Zeppin (excellent) Bacon Cheese Burger is a new version of the Zeppin Cheese Burger launched last November. The fast-food chain has sold 15 million of the burgers nationwide, its best sales ever for one product.

The Zeppin includes a beef patty double the weight of Lotteria's ordinary cheeseburger and two kinds of natural cheese.

The new version comes with a strip of high-quality smoked bacon 3.5 mm thick.

"Customers will pay if a product has a certain level of additional value," Tomoyuki Yuasa, chief planning officer of Lotteria's product division, told reporters.

The bacon cheeseburger will be priced at ¥420.

Lotteria wants the new product to account for 10 percent of overall sales. The Zeppin cheeseburger accounts for 20 percent of overall sales, Yuasa said.

Lotteria will also debut on Friday a french-fried potato that comes as a whole potato divided into wedge-shaped segments. It will come in three sizes priced at ¥270, ¥290 and ¥320.

Fast-food chains have released a series of high-quality burgers in recent years.

MOS Burger launched the Takumi burger, priced at ¥580, in 2003, while McDonald's Co. opened two outlets earlier this month, in Tokyo's Shibuya and Omote-sando districts, exclusively for Quarter Pounder burgers. The outlets, which have drawn long lines, only have two items on the menu — a Quarter Pounder with cheese set for ¥500 and a double Quarter Pounder with cheese set for ¥600. They will open until Nov. 27.