https://github.com/nagadomi/lbpcascade_animeface

DetectAnimeFace.cs

using OpenCvSharp;
using OpenCvSharp.CPlusPlus;

namespace OpenCvSharpSample.Samples
{
    public class MethodTest
    {
        public static void DetectAnimeFace()
        {
            string fileName = "image.jpg";
            string cascadeFileName = "lbpcascade_animeface.xml";

            var cascade = new CascadeClassifier(cascadeFileName);
            var srcImage = new Mat(fileName);
            var grayImage = srcImage.CvtColor(ColorConversion.BgrToGray).EqualizeHist();
            var faces = cascade.DetectMultiScale(grayImage, minSize: new Size(24, 24));
            var color = new Scalar(0, 0, 255);

            foreach (var face in faces)
            {
                srcImage.Rectangle(face, color, 2);
            }

            Cv2.ImShow("AnimeFace", srcImage);
            Cv2.WaitKey(0);
            srcImage.ImWrite("dst.jpg");
        }
    }
}