What does こなしてみせます mean?


[![enter image description
here](https://i.stack.imgur.com/gsyUi.png)](https://i.stack.imgur.com/gsyUi.png)

> 次こそは... 完璧にこなしてみせます。

This is a speech from Shikamaru, a character from Naruto manga.

The nuance is, his very first mission as a leader ended in a giant failure
with the rest of his team severely hurt and he only got a broken finger.

The above image is the moment that he vows to not fail again, which can be
translated as something like:

> Next time for sure... I'll carry out the mission perfectly!

But what makes me confused here is the phrase:

[code]

    こなしてみせます
    （熟して見せます?）
    
[/code]

I was taught that, `物を見せる` means `show something (to somebody)`, but what does
Shikamaru show here?

I have also looked up `熟す (こなす)`, which means `mature`, but `こなしてみせます` just
does not make any sense to me.




I haven't looked up dictionaries, but inferring from the Japanese animations I
have watched, こなす is something like doing something thoroughly and
successfully. The most common form I have heard is 使いこなす (to use something in
its full capability, or something like that). Never knew that it had a meaning
like "mature"; never heard that kind of usage in animations.

I do not understand why you don't understand here みせる here. It means "show",
as you said. So, he will show them his doing it thoroughly (or in current
spoken English, he will show them himself doing it thoroughly) and
successfully, next time.

