Free! Eternal Summer ED Theme:
FUTURE FISH Solo Version - Tachibana Makoto
Included as a bonus for pre-ordering Free! Eternal Summer Character Songs Vol. 1-5 at “Tsutaya" before 13 July 2014.
Credits: rangerkimmy (I was informed this is the original source, so yeah, the credit goes to her. Please do inform me if I was wrong so I could credit the original uploader).