Mandarin Companion, Level 1
John Pasden and Jared Turner
The best-executed graded readers in Chinese, and the reason is an editorial decision most of the competition did not make: they adapt Western novels — Sherlock Holmes, The Secret Garden — and reset them in China, so you already know the shape of the plot and can spend all your attention on the language. Level 1 works inside 300 characters, which is roughly HSK 2, and each book is a genuine short novel rather than a set of passages.
What it does not do: 300 characters is a real constraint and the prose is plain because of it — this is not literature and does not pretend to be. Each book is short enough that a regular reader will get through one in a couple of sittings, which makes the per-hour cost high.
Free here first: 41 graded readers here, free