I can't believe they can adapt this "all-you-can-stuff" service at this supermarket!
You can fill as much rice as you want in your lunch box with the side dish of your choice.
I can't believe they can adapt this "all-you-can-stuff" service at this supermarket! You can fill as much rice as you want in your lunch box with the side dish of your choice!
全ての内容を表現しようと思うと長くなるので２つの文章に分けてみました。
I can't believe they can adapt such a "all-you-can-stuff" service at this supermarket!
このスーパー、こんな「詰め放題のサービス」をやるなんて信じられないよ。
You can fill as much rice as you want in your lunch box with the side dish of your choice.
好きなおかずと一緒に好きなだけご飯が詰められるんだよ！
ポイントとしては「〜がすごい！」とか「すごすぎる！」というときに
"unbelievable"とよく似た表現で"I can't believe-"が便利です！
参考になれば幸いです。
all-you-can-eat」と同じように表現するなら「all-you-can-stuff」か「all-you-can-pack
It's incredible! You can take as much rice as you like with your bento box!
I know a supermarket where they let you take as much rice as you like with your bento box! It's amazing!
確かにすごいサービスですね！
「すご過ぎる」は英語で "It's incredible!", "It's amazing!", "It's unbelievable!" 等で翻訳できます。
〜放題 ＝ 〜 as much as you like 又は all-you-can-〜
"all-you-can-stuff" は文法的に問題がないのですが、聞いたことはないので上記の表現を使えばもっと自然に聞こえると思います。
bento はもう英語に成っていますのそのままで通じると思います。
It's amazing that we can pack as much rice as we want into the bento box.
It's unbelievable that the bento corner at the supermarket has an all-you-can-eat rice system.
It's crazy that they let you take as much rice as you want. On top of that, the miso soup is free!
英訳1：It's amazing that ~ で「〜なんてすごい」という言い方ができます。後ろに節をつければOK。
as much ~ as (人) want「ほしいだけの〜」。
英訳2： It's unbelievable that ~ も It's amazing that ~ と同様の使い方。unbelievable は「信じられない」ことから「すご過ぎる」と言いたい時に使えます。
all-you-can-eat で「食べ放題の」と形容詞的な使い方ができます。
英訳3：crazy は嬉しい驚きを表すのに便利な表現。日本語でもポジティブに「どうかしてるぜ」って言う人もいますね。
日本 
アメリカ合衆国 
