Uniboob / Symmastia

Symmastia occurs when the breasts are connected together across the intermammary cleft, hence the term "uniboob".

This Lycoris can recreate uniboobs, but it's not happy about it. It prefers upright poses, but can do some poses while lying down. Character LoRAs can be difficult if they were trained on nude images. It prefers small to medium breasts; large breasts can work, but like the real-life counterpart, the effect is less pronounced. Gigantic breasts do not work at all.

Use at 0.8 strength or higher to achieve the effect; lower will pull the boobs closer without the characteristic bump in the middle. This works well depending on your prompt and what LoRAs you are using. If you want a pronounced effect you can "overbake" the image by increasing the strength to 1.2-1.4, then use the generated image to create a scribble or softedge map, and add that as a controlnet input for the same seed at a much lower weight.