This craft essence is currently unavailable on the EN ver.Seaside Luxury is can be purchased from Dead Heat Summer Race! event shop.
Here is a list of servants & CEs that can be obtained for the duration of the Summer 2017 event part 1: Dead Heat Summer Race and part 2: Death Jail Summer Escape.
Rashoumon event (Ibaraki Douji event)
Murder at the Kogetsukan
Inheritance of Glory
5 Star Servants Tier List: Best Servants [5/9 updated!]
Saint Quartz Farming Guide
FGO Reroll Tier List [5/11 updated!]
Best Servants [★4]: 4 Star Tier List
How to farm EXP cards & level fast
1st Singularity: Orleans
Ryougi Shiki (Saber)
Professor and Me (Teacher and I)
Vessel of the Saint