Who Are You?

Back then in Konoha when lady Tsunade wasn't the hokage yet Naruto's friends have always seen an unknown boy in a paper bag wondering around the village. And in the academe every time Naruto was not present it just so happened that the paper bag boy would show up. But ever since Naruto became the hokage, things changed. Every time the boy in the paper bag showed up Naruto is no where to be seen.

Shikamaru had his suspicion on Naruto for a hideously long time.

What is the reason behind this?