Very interesting. But it feels like it could be fine-tuned a little.
For one, Yoko's animostity with Nia shoudl be played up more, maybe she's a bit teasing of the constipated Nia. As for Nia, her dump just seems to end as soon as it started. What could have been fun would be her returning for another round and discovering Yoko birthing a monstrous load all over hers.
Also, the start could use more fleshing out, since it does seem to kick off with Yoko hating lack of attention. Author's Response: Yeah, I'm not too happy with this one myself to be honest. Thank you for the critique, I do believe I'll be revising it in the future.