孫の手

From 麻姑 (Mako, “Magu”, a nymph in Chinese mythology) +‎ の (no, possessive particle) +‎ 手 (te, “hand”), literally “Mako's hand/claw”. Legend has it that Mako's fingernails resembled bird claws.

Compare the following verses in a poem by Tang Dynasty poet Li Bai:

明星玉女備灑掃，麻姑搔背指爪輕。 [Classical Chinese, trad.]

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明星玉女备洒扫，麻姑搔背指爪轻。 [Classical Chinese, simp.]

From: 8th century CE, 李白 (Li Bai), 《西嶽雲台歌送丹丘子》 (A Song of Parting for Dan Qiuzi on Mt Hua's Cloudy Peak)

Míngxīng yùnǚ bèi sǎsǎo, Mágū sāobèi zhǐzhǎo qīng. [Pinyin]

The Jade Girl of the bright stars prepares to sprinkle and sweep;
Magu scratches her back lightly with claw-like nails.

This term was remodelled by folk etymology into the current form of 孫 (mago, “grandchild”) +‎ の +‎ 手, i.e. literally “grandchild's hand”.

• (Tokyo) まごの​て [màgó nóꜜ tè] (Nakadaka – [3])[1]
• (Tokyo) まごのて​ [màgó nó téꜜ] (Odaka – [4])[1]
• IPA^(key): [ma̠ɡo̞ no̞ te̞]

孫(まご)の手(て) • (mago no te) 

1. a backscratcher
   • 2017, 40代になると巻き起こる老化怪奇現象の対処術‎:

     生(う)まれて初(はじ)めて、お婆(ばあ)さんが、孫(まご)の手(て)を使(つか)って背中(せなか)を掻(か)く気持(きも)ちが分(わ)かったっす。

     Umarete hajimete, obāsan ga, magonote o tsukatte senaka o kaku kimochi ga wakattassu.

     For the first time in her life, the old lady understood what it feels like to use a backscratcher to scratch her back.

     生(う)まれて初(はじ)めて、お婆(ばあ)さんが、孫(まご)の手(て)を使(つか)って背中(せなか)を掻(か)く気持(きも)ちが分(わ)かったっす。

     Umarete hajimete, obāsan ga, magonote o tsukatte senaka o kaku kimochi ga wakattassu.

     For the first time in her life, the old lady understood what it feels like to use a backscratcher to scratch her back.

     (please add an English translation of this quotation)

• → Korean: 효자손 (hyojason) (calque)