Pink

By Kyoko Okazaki. Published by Vertical. 

Softcover, 256 pages, B&W, 2013 (originally published in Japanese in 1989)

Yumiko moonlights as a call girl because her day job doesn't pay enough to feed her pet Croc. Haru an aspiring writer who has nothing to say, sleeps with a woman his mother's age not just for the money but to work on his "powers of observation". So when Yumi's step-mom turns out to be Haru's sugar-mommy, it is time for shenanigans. A little bit of drinking, a little bit of blackmail and a visit with Croc is enough to change lives and maybe add some color to a comfortable but bland life.

Daddy kept Keiko's mom as a pet; she keeps Haru as a pet; I keep Croc as a pet...Is Yumiko someone else's pet?? Is she willing to let someone care for her like that?