Furthermore, it's just a bonus item with それに〜
Grammar Explanation: In addition to with それに〜

After school, Ninako notices Ren sleeping a few seats away on the train. When Ren wakes and rushes for his stop, he knocks Ninako’s phone from her hand. The phone hits the floor, and the strap charm breaks. Ren misses his exit while apologizing and offers to replace the charm.
- 仁奈子:
- 「だっ 大丈夫
( ですっ」- “I---it's all right.”
- 「ケータイは無事
( だし!」- “Since my cell phone is safe!”
- 「それにこのストラップただのジュースのおまけだし」
- “Furthermore, this strap is just a juice prize.”
- 「しかももうだいぶ前
( 〜〜〜〜のやつで古( いから」- “Plus, it's from way back when, so it's old.”
- “I---it's all right.”
Key Points
1それに = besides that
- Ninako uses それに after saying the phone is safe, adding the strap’s low value as a second reason Ren does not need to worry.
- The flow is: “My phone is fine. Besides, this strap was not valuable.”
2Casual explanatory ending: だし
- Both 無事
( だし and おまけだし use だし to stack reasons in an informal spoken way.
3ただのジュースのおまけ
- ただの means “nothing more than”, so she downplays the strap as a cheap extra.
- おまけ means a free extra or bonus item that comes with a purchase, which matches the translation “juice prize”.
4Omitted listener-facing meaning
- The fuller idea is something like: “それに、このストラップは ただのジュースのおまけだし” with は making このストラップ the topic
- Ninako leaves part of the thought unsaid: “So it is not a big loss.”
5Tone: she is minimizing the damage
- Ninako moves from 無事
( だし to それに to おまけだし to しかも, piling on reasons because she is flustered and trying to reassure Ren quickly.
See Also
- External: Marking the topic with は and も
- Kanji: Absence and nothingness with 無
- Kanji: Matters and events with 事
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