Kei-chan and Sacchi

They are original characters of mine Juni Kei (従二慧) and Sanzen Chou (三善蝶). Juni (従二) and Sanzen (三善) are their family name, and Kei (慧) and Chou (蝶) are given name.

They call each other さっち (Sacchi) /sa̠t̚t͡ɕi/ and ケイちゃん (Kei-chan) /ke̞ːt͡ɕã̠ɴ/

Their name comes from large numbers.

Here are some additional explanations for non-Japanese speakers.

“Juni”¹ and “Kei”² means “twelve” and “ten thousand billion” respectively, so “juni-kei” equals 120000000000000000 (120quadrillion (Short Scale) | 1.2×10¹⁷) in Chinese Myriad Scale in Japanese language.

In the same way, “San-Zen”³ and “Chou”⁴ means “three thousands” and “trillion” respectively, so “sanzen-chou” equals 30000000000000000 (3quadrillion (Short Scale) | 3.0×10¹⁵).

However, they are not just rare funny name, but based on homonyms. Their family name has Sino-Japanese reading (on’yomi) and sounds somewhat like fallen noble family. Unusual, to be sure, but both are real.

I occasionally see the girl’s name Kei (慧) ⁵, but I have never seen Chou (蝶) ⁶ at all. Maybe a eccentric couple would give it to their daughter, but I don’t think it’s a terrible name.