What is the first kanji? Is it 宵?
The first kanji is 宵{よい}, yes. The character alone means evening (though sometimes also leans towards a meaning of "night" in Chinese)
宵{よい}の刻{こく}
means "evening" under this context.
Due to the constraints on size of characters and pixels, I suppose they could only write one line in the 月 part for it to still be readable. Obviously a trait of most video games of the time in Japanese (as is general awkwardness with reading some Kanji, though context does often give it away).