Takako was an unexpected baby (refer to the article of 'Soken ISHII') and she was initially called 'Tadako' (literally, 'a free child' which was named with resignation that a child was given by God for free).
高子は不幸な出生で（詳細は「石井宗謙」の項参照）、当初は「タダ子」とよばれていた（天がただで授けたものであろう、というあきらめの境地から名付けられた）。