KANAKO became 'Aunt'.

KANAKO updated Instagram and told that she had became an aunt (her brother had a baby).
She says in the comments section that "Her forehead is similar to mine".

In addition, the clothes that the baby is wearing in the photograph are gifts KANAKO gave.
This clothing brand seems to be 'Familia', and it is connected with the story that KANAKO played in the TV drama "Beppin-San"(2016).

View this post on Instagram

実は私、おばちゃんになりまして。姪っ子。ええ、可愛くてしょうがないのです。おでこは絶対私に似てると思うのです。笑 プレゼントしたfamiliarさんの洋服着てくれてるのだけど、とても着やすいみたいでドヤ顔な私??うふふ。 ・ #familiar #キアリス #べっぴんさん #BSプレミアムにて絶賛再放送中でございます #みんな元気かなぁ??

百田夏菜子 ももいろクローバーZさん(@kanakomomota_official)がシェアした投稿 - 2019年 1月月9日午後10時05分PST