黒子

Sound shift from now archaic reading 黒子(ははくそ) (hahakuso), possibly from obsolete 火(は)屎(くそ) (hakuso, “burnt ash”).[1] Attested as ほくろ from the 17th century; readings of ははくそ and はくそ are both attested from the 9th century. Other historical readings include ははくろ (hahakuro, 13th century) and ほうくろ (hōkuro, 13th to 15th century).[1]

黒子(ほくろ) or 黒子(ホクロ) • (hokuro) 

1. a mole or nevus containing more melanin than surrounding skin
   • 1982, Miura Ayako, Teiryū chitai [Mudslide zone], page 3:

     良(よし)子(こ)の右(みぎ)の耳(みみ)たぶには大(おお)きなほくろがあったことを思(おも)い出(だ)し、耕(こう)作(さく)は耳(みみ)たぶを見(み)た。

     Yoshiko no migi no mimitabu ni wa ōki na hokuro ga atta koto o omoidashi, Kōsaku wa mimitabu o mita.

     Remembering that Yoshiko had a large mole on her right earlobe, Kosaku looked at the earlobe.

   • 1999, Miyazawa Michi, Ninsō shindan [Decoding faces], page 137:

     ホクロには生(い)きボクロと死(し)にボクロがありますが、基(き)本(ほん)的(てき)にはエネルギーバランスが過(か)剰(じょう)な部(ぶ)位(い)に表(あらわ)れます。

     Hokuro ni wa ikibokuro to shinibokuro ga arimasu ga, kihonteki ni wa enerugī baransu ga kajō na bui ni arawaremasu.

     Moles can be divided into life moles and death moles, but fundamentally they reveal an excess of energy balance in some part of the body.

2. short for 入黒子 (irebokuro): a beauty spot drawn or placed on the face

Usually written in kana.

• ほくろ on the Japanese Wikipedia.Wikipedia ^ja

Sound change from 黒衣 (kurogo).

黒子(くろこ) • (kuroko) 

1. stagehand in kabuki and bunraku (who dresses fully in black)

• 黒(くろ)衣(ご) (kurogo)