I know quite a number of people who do this, but I just want to know for sure. The blog is non-commercial and dedicated to a manga. It's for sharing and other fans to browse.
Do you have an explicit permission by the artist? Does the artist give a blanket permission to anyone which covers this kind of use of their work (a license)?
If no, then you commit a copyright violation when you use their work for your blog.
This applies to practically any country which signed the Berne convention which is almost everywhere in the world. Having no commercial interest is usually not an excuse to violate copyright. Regarding which jurisdiction applies when you, your website and the copyright holder are in different countries: I opened a new question about this.