Wat kind of mask?:
Medical mask:
http://www.mangago.zone/read-manga/oujisama_dochirasama/
http://www.mangago.zone/read-manga/megumi_and_tsugumi/
http://www.mangago.zone/read-manga/hoezura_ni_kamitsuku_kisu/
http://www.mangago.zone/read-manga/mask_danshi_wa_koishitakunai_no_ni/
http://www.mangago.zone/read-manga/cryptic_white/
http://www.mangago.zone/read-manga/akakute_amai/
Kitsune mask:
http://www.mangago.zone/read-manga/canvas_ni_kuchizuke_o/mf/v01/c006/1/
Other masks:
http://www.mangago.zone/read-manga/fukumen_danshi/
http://www.mangago.zone/read-manga/kamengoshi_ni_kiss/
http://www.mangago.zone/read-manga/just_when_i_thought_i_came_here_to_die/
http://www.mangago.zone/read-manga/koi_wa_kamen_no_uchigawa_ni/
manga where the uke i think is sensitive to smells and so he always wears a mask... i dont know much other than that.... help :(((