Japanese phrase
だれにも言わないと約束します。 da re ni mo i wa na i to yaku soku shi ma su
Meaning
I promise not to tell anyone.
When to use it
Promises to keep a surprise private until the right time. It sounds sincere and reassuring when a friend asks.
Example dialogue
誕生日のサプライズ、当日まで秘密にしてくれる？ tan jō hi no sa pu ra i zu tō jitsu ma de hi mitsu ni shi te ku re ru
Can you keep the birthday surprise until the day itself?
だれにも言わないと約束します。 da re ni mo i wa na i to yaku soku shi ma su
I promise not to tell anyone.