A Pony Diffusion XL finetune by Minthybasis. Like Novelaiv3, this model is trained on a highly diverse dataset with artist tags with the intention of allowing users to use it as a one for all model for all purposes. According to the author, the 0.4.5 ersion is trained on 500k pictures from dataset which were been captioned with Claude 3 OpusVision, then pruned and converted to booru hybrid. The name 4th tail is a legacy remnant of the model's original intended purpose, which was generating foxgirls.
See 5th tail for the similar concept but as an AnimagineXL finetune.