Do i need to play the first?

[Mister Shan]

Or would reading a synopsis suffice?

[Vakuda]

"Kando: It's been 14 years since the last game, so we tried to create a new game experience that could be enjoyed even if you weren't familiar with the previous installment. Instead of a sequel, we thought about a new story with a shared worldview. The main character has shifted from Neku to Rindo, and the gameplay has also changed drastically from the original TWEWY. In that regard, we didn't want to use a title that emphasized the nature of a sequel like "The World Ends With You 2". That's why Nomura came up with the title, "NEO: The World Ends With You"."

[subb]

its better if you play the first game first but aside from a few stuff in the final day you can understand the plot perfectly fine
with that said tho, the game isnt really afraid to spoil a couple big parts of the original game when it needs to, so make that what you will and i hope you have fun with whichever one you start with

[zakalwe]

I would honestly play the original first, it's an amazing game. Even the Final Remix version, which you can get on mobile/ipad and I believe Switch (if you don't own a DS).

DS is the best way, though, with the unique dual screen combat.

[Khelder]

The first game is brilliant, and well worth playing if you have the opportunity. If you don't, then you could watch a synopsis, or you could look up the anime (free on the Funimation website in some countries) — while it rushes through and skips over a few points, it covers everything necessary for NEO.