Running an Island in Another World with a Yandere Big Sister?

(Also known as: After getting a random loot-box golden finger and being stranded on a deserted island in another world with a big sister, we're forced to huddle together for warmth!)

I transmigrated to another world and got stranded on a deserted island with a big sister who likes me. I even got a little box that gives me a different item every day?

So why does it keep giving me such weird stuff...

After failing to find fresh water, the big sister and I were forced to drink half a bottle each of the charm potion we'd gotten from the box.

Watching the big sister become more and more unhinged, and feeling myself getting more and more out of sorts, Bai Nai finally chose to... stop thinking!

A few days later, Bai Nai woke from a night of exhaustion and deeply regretted giving in. At this rate, I might not starve to death, but I'll definitely work myself to death!

(Transformation + deserted-island survival in another world? + one-on-one romance + management + loot boxes + daily life)