年子 としご
toshigo

Noun

1. child born within a year of another; children born in consecutive years

いもうと咲子 さきこです。俺 おれ年子 としご、今 こん受験 じゅけん せいです。
imōtono sakikodesu. oreto toshigode konjukensēdesu.
This is my little sister Sakiko. She was born the same year as me and is now studying for her exams.