Do manga artists draw their comics by hand or use computers? In the Bakuman manga, the authors show that the manga artists create a manga without using any technology like computers. Is that how the mangas are drawn?
Every artist has different drawing techniques. 


Some fully use the computer (using a drawing tablet and photoshop)
Some fully draw by hand (using pencil, then pen, then erasing the pencil, the making the pen lined bolder)
Some use a combination of the two (Draw by hand, scan to computer, complete with photoshop).


It's really up to the artist.