Yusuke, Botan and others in “Unfinished Business”

Botan! Please, there's gotta be something I can do!

Botan

I'm sorry, Yusuke. I've tried everything in my power.

There is one way...but you may not be willing to do it.

I'll decide that for myself! Tell me!

You can save her life by using the power that's been gathered by the Spirit Beast you've been carrying with you.

What? [pulls out the egg] You mean this little guy?

Throw it in the fire, and it will unleash from the egg and save her.

And that's all I have to do? Why didn't you say so?

But if you hatch the Spirit Beast now, before it's ready, it won't be able to perform its usual duties.

Botan

So does that mean...if he saves Keiko's life, the beast won't be able to bring Yusuke back?

Right. Yusuke will never have a chance to be alive in this world again.