'Why?'
'Because you are not Miyuki!'
The elf opposite, although capable of imitating Miyuki's appearance, clearly didn't understand Miyuki's personality and nature. After just a few rounds of simple conversation, Renji became certain of this.
For example, when the topic of "that matter" came up, the shyness exhibited by the elf might be a normal reaction for a typical woman, but the problem is, Miyuki is not a typical woman. The word 'shy' would never apply to the real one.
Moreover, even the imitation of appearance wasn't perfect. Renji confirmed his earlier suspicion.
Miyuki wouldn't be that big!
That size was definitely not Miyuki! Don't underestimate his ability to recognize the true from the false after having ogled the game character portraits hundreds of times!
Renji cursed inwardly and maintained his distance from the elf women, who only resembled Miyuki in appearance.