11-day trip to Tokyo, Kyoto, Nara, Osaka, Hakone, Hokkaido and Kanazawa

I believe you have enough time to visit all the places you listed, but since Hokkaido is very far away, it is possible to go, but maybe you would want to have more time to spend there because of the price of flight tickets that average around $500. In any case, take a look at this suggestion:

From March 30th - To April 4th
you could do this perfect 6-day itinerary from Tokyo to Osaka:
-Essence of Spring Tour | Cherry Blossom Festival (from Tokyo to Osaka)
https://triplelights.com/japan/activity/tokyo-essencespringcherry-blossom-festival-from-2245
This includes all tours, hotel, and transportation, also the pickup from your airport.

April 5th From Osaka to Kanazawa (Ishikawa) and Kanazawa tour
From April 5th, you will need to take the trains and find hotels by yourself (you will have learned the system by then, so you can do it). You can take a very early train and arrive in time for an afternoon tour. Then you can sleep, take another half-day tour the next day morning and then go back to Osaka to take your airplane to Hokkaido.
This guide Irukishi has two tours in Kanazawa, he could do two half day tours for you:
Kanazawa Half Day Tour - https://triplelights.com/japan/tour/kanazawa-kanazawa-half-1533
Kanazawa Walking Tour - https://triplelights.com/japan/tour/kanazawa-kanazawa-walking-1532
I recommend booking the half-day tour to save your date. When you do so, you will be in contact with your guide, then you can plan the following day.

April 6th - Half-day Kanazawa tour in the morning than back to Osaka for Sapporo (Hokkaido) Flight
Please take a look at the flights. you could take this 19:45 flight to Sapporo from Osaka:
https://www.google.co.jp/flights/#search;f=ITM,KIX,21Y;t=CTS,OKD,23Q;d=2018-04-06;r=2018-04-08;sel=KIXGMP0KE2728-ICNCTS1KE765

April 7th - Sapporo Tour
https://triplelights.com/japan/tour/hokkaido-sapporo-1730

April 8th - Hakodate Tour
https://triplelights.com/japan/tour/hokkaido-hakodate-8-hours-2009

April 9th - Return to Tokyo
You can return to Tokyo from Hokkaido by airplane (you will need to take a look at flights) and you will have enough time to prepare for your flight back to your country on the 10th.
If you want, you can finish your time in Japan with the golden key by having a real Japanese Home experience on the night when you arrive on April 9th
Japanese Culture Experience At Kahoko's Home:
https://triplelights.com/japan/activity/tokyo-japanese-culture-experiencekahokos-home-636

I think this is the best itinerary for you to make the most out of your Japan trip during the days you have available.
I Hope its useful!