How can I display one data point in line chart

I’m going to make a line chart from a lot of time series data.
But since a lot of data, I can’t find What data is in some point…
In short, I want to make this
image
to
image
print olny one or a little data by nearest point by mouse.

Is there a way to solve this problem?..
Please give some keywords or layout options…
Thank you.