Tokyo leg of Japan trip: doable?

Hi all! I'd like some advice on whether each of these days are doable. Is it too packed? Thanks!
Also, is it worth slotting in the Shibuya crossing or Shinjuku Gyouen? If so, what should I replace or where can I fit it in?

Day 1:
Train from Shin-Osaka to Shinagawa Station (~3hrs)
Ikebukuro: Animate, Tokyu Hands, Pokemon Centre, Sega Arcade
Shin-Okubo (~2hrs)

Day 2:
Harajuku: Probably going to skip Takeshita Dori. Instead going to visit cat cafe, Kinji, Kiddy Land.
Shimokitazawa

Day 3:
Ueno area: Ueno Park, Ameyoko, Nippori
Odaiba: Miraikan, Round 1 arcade, Trick Art Museum

Day 4 (last day):
Ghibli Museum (will be booking tickets soon)
Nakano Broadway
Flying out of Narita at 8pm

Yup on issues. Not rushed.

When is this trip in relation to today? Only think "iffy" is the tickets for the Ghibli Museum, as they tend to sell out fast and are available 3 months out.

Also, is it worth slotting in the Shibuya crossing or Shinjuku Gyouen? I

Well these are two very different destinations. Shibuya crossing will only take you 5 , max 10 min to see. Shinjuku gyouen probably at least an hour.

I would build in Shibuya crossing in the day you do Harajuku and Shimokita. Just take Yamanote kind to Shibuya then walk over Shibuya crossing, then take the escalator up to Keio Line, walk a few steps back to see Shibuya crossing from above and take the next train (both express and local are fine) to Shimokitazawa.

Depending on the time of the year Shinjuku Gyouen is very nice, but it needs time.

Enjoy your trip to Japan!