Not sure how to clean this...

[BAVy]

I'm not sure if i can level this right... Moreover, there are white areas on some frames and text bubbles are pretty clean... It kinda seems like the borders and backgrounds are not supposed to be white in this manga...???
http://i.imgur.com/PiCjduv.jpg
http://i.imgur.com/HZNZEeM.jpg

 

[Mana Light]

Yes. You're right. Don't clean it.
imo it is like color page but was converted into grayscale mode already.

 

[BAVy]

imo it is like color page but was converted into grayscale mode already.

Ikr
But there are some colored pages in the beginning of the volume, so I don't think that's the case

 

[Mana Light]

That is the case. I mean mangaka did it on purpose. He didn't add tones to his drawing.
http://www.clipstudio.net/en/functions

"Directly converts a drawn content into a halftone dot “tone” simply by turning on “Tonization” for a layer "