What anime name are these two characters lying in the grass from? I have been searching this name for weeks!!
Could you help me out?
It's from a visual novel named Koijibashi, according to the tag on the same image on Sankaku Channel.

It is released on 2004-August-13 for Windows platform.
Synopsis (translated from Koijibashi's article on Japanese Wikipedia):

Looking forward to their graduation in March, Tachibana Yuuta, together with his classmates Katakura Hadzuki, Ichinose Ryuu and his childhood friend Konno Nonoka, make a plan to go on a graduation trip together during spring break.
From Yuuta's casual remark, the destination is decided, by Sagara Shiho - Yuuta's cousin who happens to be there, to be a rural town with the suspension bridge named &quot;Koijibashi&quot; (Love Bridge?), which has the legend to tie people's fate together. However, the legend of &quot;Koijibashi&quot; as it is passed down is not your usual pleasant story, and unforeseen mysteries awaits Yuuta and co.