Safer when lit up with 安全
Kanji Explanation: Peace and ease with 安

At a nighttime festival, Sacchan, Yui, and Kotoha receive glowing star necklaces to wear. After some time, Sacchan’s mother arrives to pick them up.
- 結衣:
- 「あ 私
( のピカピカもう電池( 切( れちゃった」- “Ah, my sparkler's battery has already run out.”
- 母
( さん: - 「あらま 光
( ってる方( が安全( でいいのに」- “Oh dear, it's safer and better when it's lit up.”
Key Points
安全
( = “safe” in a practical nighttime senseHere, 安全
( means being safer because the girls are easier to see in the dark.
光
( ってる = casual spoken form of 光( っている光
( ってる is a common contraction of 光( っている, meaning “is glowing”.Recognizing this contraction helps you parse the line quickly in natural dialogue.
光
( ってる方( が = “the glowing state is the better option”方
( is used when comparing alternatives, so 光( ってる方( が means “the lit-up one” or “when it’s lit up”.The unstated comparison is with not glowing anymore, since Yui just said the battery ran out.
安全
( でいい = “safer and better”The sentence links 安全
( and いい to say that the glowing state is both safer and preferable.
Sentence-ending のに adds a mild “that’s a shame” feeling
Here, のに does not start a full contradiction; it works like a soft lament that it would have been better if it were still glowing.