I say that because I thought it up with だって

Grammar Explanation: That said with だって

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!”; Literal: “Because the one who thought up this kidnapping case was Akiko!!”

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.

I say that because I thought it up with だって

Key Points

See Also