data modify entity @s[nbt=!{Item:{tag:{diamondnetherarmorkyu:1b}}},nbt={Item:{id:"minecraft:diamond_helmet"}}] Item.tag merge value {diamondnetherarmorkyu:1b}
data modify entity @s[nbt=!{Item:{tag:{diamondnetherarmorkyu:1b}}},nbt={Item:{id:"minecraft:diamond_chestplate"}}] Item.tag merge value {diamondnetherarmorkyu:1b}
data modify entity @s[nbt=!{Item:{tag:{diamondnetherarmorkyu:1b}}},nbt={Item:{id:"minecraft:diamond_leggings"}}] Item.tag merge value {diamondnetherarmorkyu:1b}
data modify entity @s[nbt=!{Item:{tag:{diamondnetherarmorkyu:1b}}},nbt={Item:{id:"minecraft:diamond_boots"}}] Item.tag merge value {diamondnetherarmorkyu:1b}