Light bondage and humiliation play, as well as the mc being a acousticophile (someone who is sexually aroused by an auditory stimulus- in this case, his partner's voice).
Souhei asks Lucas to tie him up (light bondage).
First two chapters feature Rogi tied up.
Tatsuyuki is blindfolded halfway through chapter 6, and is gagged with a horse bit and bound with rope in the beginning of chapter 7. Warning!! These two chapters show non-consensual sex/rape.
I LOVE this manhwa. One of the best, if not the best, representation(s) of BDSM I've seen in Yaoi.
Chapter 3 features incest with younger brother and older brother. Older brother is dominated by younger brother after younger brother learns his older brother frequents an SM club.
Volume 1, Chapters 1-4 and Volume 2, Chapters 7-8 and 11.5 follow Chairman Kanou, a timid man scared of being rejected because he's gay, and his subordinate, Sawamura, who is handsome, but secretly a sadist.
Former celebrity Son Young Woo found his life to be boring, and decided to spice it up by seeking out a Dom to humiliate him and treat him like a slave. Out of the many replies he received to his request, he decides upon 28 year old Junior High teacher Kim Joo In. This is the story of their relationship.
Tagasaki Mitsu, a second year transfer student, has a biting fetish, and has engaged in BDSM with partners to test the depths of their love for him.
Chapter 5: Togami's relationships always end up in violent break-ups, and can't figure out why. In order to find out, he enlists the help of a psychiatrist named Hattori Ryogo....
I Am Your Pavlov Dog