I suppose you know I went to Pokemon event “Pikachu Outbreak!” last time.
(Past Article:
Pikachu Outbreak! (Pikachu Tairyo Hassei Chu) in 2017 ~Lots of Pikachu take over Minato Mirai~
Pikachu Outbreak! in 2017 ~Pikachu Walk and Stage Show!!~)
There were some temporary shops in the place, and I found souvenirs packed in Pikachu package!!
They were sold like following↓↓

So cute(´ω`)
The original is Yokohama Harbour which is a famous souvenir sweet of Yokohama. The producing company ARIAKE Co.,Ltd seems to have developed a new flavor Milk Lemon for Pokemon Harbour.
I bought the one having 8 pieces!!

There is also a pikachu under the wrapping!!

Each package is also cute.
The inside sweet is like this. Quite simple shape lol
It has sweet white bean paste and sugaring lemon inside. The lemon makes the flavor fresh. It must match to some tea. I like it.
I cannot find the information Pokemon Harbour is seasonal or not, but it is only sold in physical stores. The online store does not deal with it. (Note: Their online store is only available to Japan).
The company stores, all Pokemon Centers in Japan, some department stores, some souvenir shops in Yokohama, etc. have it.
My place is near from Yokohama, so, I haven’t bought Yokohama souvenir. Honestly, I didn’t know Yokohama Harbour lol But I will buy regular Yokohama Harbour in near future!!!

Regular flavor has chestnut paste instead of bean taste.
Reference:
Yokohama Harbour WEB site (All written in Japanese)