In Direct QSL envelope, I use on a Japanese-like stamp. That is cute-art or manga, also cool design as Japanese.
It's an official stamp from the Japanese post office, approved by the Japanese government, so it's official as legal stamp.
This is a formal stamp that is neither a toy nor a play.
However that stamp price will not enough to cost for airmail in many case. so maybe will add standard one stamp.
ex: If the sale timing is right, you can buy it normally at a Japanese post office.
特に海外の方に言いたいのですが、私は出来るだけ日本文化らしい切手を貼ってます。中にはアニメ風のものもありますが、これは公式な切手であり、おもちゃや悪戯ではありません。
Everything is due to my unfamiliarity. I sincerely apologize. sorry…
I will be careful after, so please do your helping possible.
2021年頃、いくつかのDX向けQSLカード送付にSAEを入れ忘れています。現在は気を付けていますが、未入の際は何卒ご容赦ください。