This hairstyle is available in two lengths. The standard length is tailored for SDT gameplay. The extra-long version is more faithful to the original character design, but will tend to clip through the floor.
Was linked in a character pack fro Highschool DxD, which was the 4th post when using the "Search" function in the top right and typing "Akeno" btw.
Please understand that I'm not saying all of this to be mean. Providing useful reference images will greatly increase chances of the request being filled.
Side-view is essential: almost nothing can be done if the hair or costume is not shown exactly from the side (i.e. 90°)
Anime-style is essential: it means two or three colours (base, shadow, light reflection) with no or very simple gradients. Photographs, 3D game screenshots, digital "waterpainting" pictures, etc. have colour gradients very difficult to reproduce.
High resolution is essential: very pixelated refs makes drawing small parts quite difficult to reproduce (find PNG or JPG images, not BMP).
Upload your references on an offsite image hoster (e.g. Imgur) and put them in image tags
When requesting hair, always specify static or dynamic. Note that dynamic is harder to make and less likely to be done.