未来日記 1

It's alright

I read the story in English years back, but even then the vocabulary is fairly simple. If you're at an N3 level you should be able to understand the story, maybe even at an N3-ish level with some dictionary-aide.

There is full furigana, except in the scenes where the character is looking at their phone, but the language used is fairly simple in those, and the MC will often repeat what was written. Overall, it could even be a good first manga if you think you're ready, or an easy read if you already got some manga under your belt. I'm around an N3 level and I was able to understand it with basically no dictionary, minus a word or two.

As for the story... it's alright. The art is alright and the premise is interesting, but I think the anime is a lot better if you're looking for some action. I'm just not a big fan of the writing style, but it's up to you.