COCC-16318: Miracle Happy Day / Lisa (CV: Aki Toyosaki)

[whatkind]

Why is "i" added next to "Day"? i is useless.
"Day"'s formal Katakana write is デー, and its pronunciation is [de-/dee].
Usually Japanese also pronounce えい/エイ[ei] as a long vowel [e-/ee].
And in fact, the formal pronunciation of ディ is [di] like Nadia: ナディア because it is grammatically regarded as one letter including the small ィ.
But in this title, it should be regarded as two letters デ+ィ and pronounced as [dei]. Of course strictly speaking, [i] should be slightly weakly pronounced.
If Dayi were right, the Katagana write should be デーィ.