NNG Why...

 Felt like doing a quick digital watercolour, and something sad.

Tsuyomi, even though she was engaged to Zashi, she couldn't help but worry for both Kaguya and her mother's condition (which has worsened from her grieving). She even went and consulted Hikaru, who at first didn't want to talk to her about Kaguya, still feeling resentful for being used to act as a boyfriend. After some convincing he explained to her why he did what he'd done earlier, bluntly saying...

"Label me the villain for all I care, but it isn't fair to deceive a girl like her into believing a lie her own over-protective family concocted. Had I known the exact reason before I was hired, I would've refused. And don't tell me to chase your sister, your family put her through enough deception, and on top of it made me a part of it. My presence would only pain her more. Why don't you let her for once be her own shinobi? Your family may not know it but I reckon she's just as capable being a shinobi as you and me..."

And that was the last she'd seen of Hikaru. In NNG II he was later killed in action while embarking on a dangerous mission. 

Tsuyomi, art (c) Me