Kissmanga was not the official source for the manga uploaded on their site. Similarly, Kissanime hosted popular anime without any rights to stream these videos. Both sites were claimed for copyright and taken down. It is rumored that other popular non-official sites could meet the same fate. It is still not clear why the site was shutdown suddenly. Sites like Kissanime have existed for over a decade and came back after persistent attacks. The story was broken on Reddit after the Kissanime support page announced it on their twitter handle. Many fans who prefer this site are now looking for alternatives. As Kissmanga is no more, here are some of the official and non-official sources to read manga online. Each site has its pros and cons and you will need to visit them to find a suitable replacement.
Official
Viz(MANGA Plus by SHUEISHA)
This company is the main distributor of manga outside of Japan. They sell manga in printed copies as well as digitally. You can buy the entire volume of your favorite manga to read it in comfort. They also have a partner site Manga Plus sponsored by Shueisha that uploads the newest chapter for all major manga releases in the Shonen Jump Magazines (Monthly and Weekly). The chapters are translated in English as well as Spanish. Mangaplus only has the latest and starting a few chapters of each manga. You need to sign up for a premium to unlock the entire manga.
Bookwalker
This is a Japanese site that sells digital comics and manga. You can find many popular ones here to buy and read. There are even some free ones on the site as well.
Comic Walker
You can find a large number of free manga to read on this site. These are released by the publisher in both English and Japanese versions.