The Empress of the Inazuma region is an electro character and before unleashing thunder on the enemy you will first need to upgrade the Shogun a little. Here is the complete list of the materials needed for Raiden Shogun.
Raiden Shogun Ascension Materials

Vajrada Amethyst Sliver
Number required: 1

Vajrada Amethyst Fragment
Number required: 9

Vajrada Amethyst Chunk
Number required: 9

Vajrada Amethyst Gemstone
Number required: 6

Storm Bead
Number required: 46

Amakumo fruit
Number required: 168

Old Handguard
Number required: 18

Kageuchi Handguard
Number required: 30

Famed Handguard
Number required: 36
Raiden Shogun Talents Upgrade Materials List

Old Handguard
Number required: 18

Kageuchi Handguard
Number required: 66

Famed Handguard
Number required: 93

Teachings Of Light
Number required: 9

Guide To Light
Number required: 63

Philosophies Of Light
Number required: 114

Molten Moment
Number required: 18

Crown of Insight
Number required: 3

Five star characters aren't always the best and Sayu just proves it once more with her performances during the Divine Ingenuity Event