<div class="photo">
  <img src="https://www.nan-demo.work/wp-content/uploads/2022/07/img05.jpg">
  <img class="nikoniko" src="https://www.nan-demo.work/wp-content/uploads/2022/07/smile.png">  
</div>

div,p,img,figure,ul,li {
  padding:0;
  margin:0;
  display: block;
}

img {
  width:100%;
}

.photo {
  width:500px;
  padding:4rem;
  position: relative;
}

.nikoniko {
    width: 130px;
    position: absolute;
    top: 0;
    right: 0;
    animation: shake 2s infinite;
    transform: rotate(20deg);
}

@keyframes shake {
    50% {
        transform: rotate(-20deg);
    }

    100% {
        transform: rotate(20deg);
    }
}