Japanese with Manga
Learning through examples in manga

I say that because I thought it up with だって

Grammar Explanation: That said with だって

Manga panel from 名探偵コナン showing example of I say that because I thought it up with だって.
名探偵コナン » Volume 1 » Page 111

A fake kidnapping ploy turns into an actual kidnapping. After the kidnapped child is safe, her father goes after their butler for concocting the scheme. The daughter, Akiko, protects the butler, saying she’s the bad one.

晶子(あきこ):
「だってこの誘拐(ゆうかい)事件(じけん)を考(かんが)えたのは、晶子(あきこ)なんだもん！！」
“I say that because I'm the one who thought up the kidnapping plot!”

Key Points

  1. だって gives the reason for what she just said

    • Here だって means “because” in an emotional, childlike defense.

    • Akiko is explaining why she said she is the bad one.

  2. だもん adds childish insistence

    • Final だもん sounds like an emotional justification a child would make.