It's slightly funny to be writing an English language review for a book I read in Japanese and that isn't actually formally available in English, but here we are. In fact, this was actually the first book I've read in Japanese purely for fun, rather than for a translation, and I greatly enjoyed it.
For a start, it's consistently adorable. The art is very cute, the characters are all endearing and Maruko herself provides a great window to get to know her world from. The world of Shizuoka prefecture in the Showa era is a very different one than the England of the late/early millennium I grew up in, but all the stories are told so fondly and engagingly that it made me feel nostalgic for a childhood I never had or could have had, so it's a huge success for that.
It's not just cute and nostalgic either of course, it's also very consistently funny. From stories like a somewhat embarrassingly low key children's Christmas party, a visit from younger cousins for a holiday, Maruko's distress at an upcoming marathon and so much more, I was regularly laughing throughout the book. Maruko's precociousness just brings a lot of laughs and sweetness together and it works wonderfully.
The bonus chapters without Maruko, taken from other autobiographical manga by the author, are a genuine bonus, too. Mostly a collection of one-off stories, with one two parter, they're just as funny, endearing and nostalgic as the actual Chibi Maruko-chan stories themselves and provide interesting, different perspectives as we get stories from other parts of Sakura's life, such as one about her visiting a disco as a teenager. The one about her being desperate to get a nosebleed as a child in this section is a real highlight as comedy goes!
This is a great, funny, heartwarming manga and it's a real shame it's never had an official English release. As it stands, though, it's a very good book to pick up for Japanese language learners, although it should be noted that it's quite wordy for a manga, so I'd recommend it for people who are a bit more confident in their Japanese, rather than total beginners.