Speaking of chicken burgers, the "Teriyaki Chicken Burger" of Mos Burger (https://franchisejapan.biz/story/2495/) is well known in Japan. 
With its savory chicken is slowly grilled over an open flame. The crisp lettuce complements the perfect combination of sweet soy sauce and mayonnaise, reminiscent of yakitori, to create the original Japanese style burger.

On August 23, a yakitori specialty izakaya restaurant “Torikizoku” opened “Toriki Burger” in Otemachi, Tokyo. The restaurant is decorated in the symbolic yellow and red colors of Torikizoku, and sells eight types of chicken burgers at the same price as Torikizoku, 390 yen for a single burger and 590 yen for a set. https://toriki-burger.co.jp/

Dining Innovation (https://franchisejapan.biz/story/3222/), which has developed hit brands such as "Yakiniku Like," a restaurant specializing in one-person yakiniku opened a chicken burger specialty restaurant called "DooWop" in Daikanyama, Tokyo on July 20. Despite being under a Corona emergency declaration, it was reported that there was a line of customers, mostly students and young women, on the first day of the opening. DooWop's main product, Chicken Burger, is a large size fried chicken thigh sandwiched between  buns and a choice of six different sauces, including BBQ eggs. DooWop's ordering is done only by pre-ordering through its own app and self-checkout at the store, and as data is accumulated in the future, automatic ordering is expected in the future. https://doowop.co.jp/

On May 29, Royal Holdings, operating a family restaurants chain such as “Royal Host,” opened “Lucky Rocky Chicken”, a buttermilk fried chicken restaurant in Musashikoyama, Tokyo. https://lr-chicken.jp/

Chicken burgers are originally popular in China. In the U.S., chicken burgers with fried chicken in between became very popular in the U.S. in 2019 and long lines formed. It still now the competition among brands seems to be continuing.

As well in Japan, now the race for the chicken burger market share has started.
Unlike pork and beef, chicken has low religious barrier, so there are high expectations for global expansion.