蘿藦[Gagaimo]
Metaplexis japonica
In the past, this was represented by combining with the Chinese name with the Japanese pronunciation kagamiimo, namely, an ateji. And, the prevailing theory is that this kagamiimo gradually changed through phonetic shift to become gagaimo.
Words consisting of two consecutive identical sounds are commonly found in young children's vocabularies. For example, 着物[Kimono] is bebe; 草履[Zōri](Japanese sandals) is jojo; 魚[Sakana](fish) and 鳥[Tori](bird) are toto; 爺(grandfather, elderly man) is jiji; 婆(grandmother, elderly woman) is baba; 父(father) is chichi, toto, tete(old expression); 母(mother) is haha, kaka; and so on. Even adults use these family-related words. And, in some dialects, 母 seems to be called gaga.
In 遠野物語[Toono Monogatari](Tales of Toono) compiled by 柳田 国男[Yanagita Kunio](Folklorist, 1875-1962), there is a tale where the mother is referred to as ガガ[gaga]. Incidentally, regarding that tale, Novelist 三島 由紀夫[Mishima Yukio](1925-1970) mentioned things like that even Prosper Mérimée(French novelist, 1803-1870) would have to respect it, and, if you read this carefully and appreciate it, you will come to understand what a novel really is. I will include the previous tale for clarity.
一〇 此男ある奧山に入り、茸を採るとて小屋を掛け宿りてありしに、深夜に遠き處にてきやーと云ふ女の叫聲聞え胸を轟かしたることあり。里へ歸りて見れば、其同じ夜、時も同じ刻限に、自分の妹なる女その息子の爲に殺されてありき。
[Jū Kono otoko aru okuyama ni hairi, kinoko wo toru tote koya wo kake yadorite arishi ni, shin'ya ni tooki tokoro nite "Kyā!" to iu onna no sakebigoe kikoe, mune wo todorokashitaru koto ari. Sato e kaerite mireba, sono onaji yoru, toki mo onaji kokugen ni, jibun no imouto naru onna sono musuko no tame ni korosarete ariki.]
Ten: When this man had entered a deep mountain, built a hut to stay for gathering mushrooms, he heard a woman's scream "Kyaah!" coming from afar, and it made his heart skip a beat. Later, when coming back to the village, he knew that on that same night and at the same time, his sister had been killed by her own son.
一一 此女と云ふは母一人子一人の家なりしに、嫁と姑との仲惡しくなり、嫁は屢親里へ行きて歸り來ざることあり。其日は嫁は家に在りて打臥して居りしに、晝の頃になり突然と倅の言ふには、ガガはとても生しては置かれぬ、今日はきつと殺すべしとて、大なる草苅鎌を取り出し、ごし/"\と磨ぎ始めたり。その有樣更に戲言とも見えざれば、母は樣々に事を分けて詫びたれども少しも聽かず。嫁も起き出でゝ泣きながら諫めたれど、露從ふ色も無く、やがては母が遁れ出でんとする樣子あるを見て、前後の戶口を悉く鎖󠄁したり。便用に行きたしと言へば、おのれ自ら外より便器を持ち來りて此へせよと云ふ。夕方にもなりしかば母も終にあきらめて、大なる圍爐裡の側にうづくまり只泣きて居たり。伜はよく/\磨ぎたる大鎌を手にして近より來り、先づ左の肩口を目掛けて薙ぐやうにすれば、鎌の刃先爐の上の火棚に引つ掛かりてよく斬れず。其時に母は深山の奧にて彌之助が聞き付けしやうなる叫聲を立てたり。二度目には右の肩より切り下げたるが、此にても猶死絕えずしてある所へ、里人等驚きて馳付け伜を取抑へ直に警察官を呼びて渡したり。警官がまだ棒を持ちてある時代のことなり。母親は男が捕へられ引き立てられて行くを見て、瀧のやうに血の流るゝ中より、おのれは恨も抱かずに死ぬるなれば、孫四郞は宥したまはれと言ふ。之を聞きて心を動かさぬ者は無かりき。孫四郞は途中にてもその鎌を振上げて巡査を追い廻しなどせしが、狂人なりとて放免せられて家に歸り、今も生きて里にあり。
[Jū-ichi Kono onna to iu wa haha hitori ko hitori no ie narishi ni, yome to shūto tono naka ashiku nari, yome wa shibashiba oyazato e ikite kaeri-kizaru koto ari. Sono hi wa yome wa ie ni arite uchi-fushite orishi ni, hiru no koro ni nari totsuzen-to segare no iu niwa, "Gaga wa totemo ikashite okarenu, kyō wa kitto korosu beshi" tote, ookinaru kusakarigama wo toridashi, goshi-goshi to togi hajime tari. Sono arisama sarani tawamuregoto tomo miezareba, haha wa samazama ni koto wo wakete wabitaredomo sukoshi mo kikazu. Yome mo oki-idete naki nagara isame taredomo, tsuyu shitagau iro mo naku, yagatewa haha ga nogare iden to suru yōsu aru wo mite, zengo no toguchi wo kotogotoku tozashi tari. "Ben'yō ni ikitashi" to ieba, onore mizukara soto yori benki wo mochi kitarite "Kore e seyo" to iu. Yūgata nimo nari shikaba haha mo tsui-ni akiramete, ookinaru irori no katawara ni uzukumari nakite itari. Segare wa yoku-yoku togi taru oogama wo te ni shite chikayori kitari, mazu hidari no kataguchi wo megakete nagu yōni sureba, kama no hasaki ro no ue no hidana ni hikkakarite yoku kirezu. Sono toki ni haha wa miyama no oku nite yanosuke ga kikitsukeshi yōnaru sakebigoe wo tate tari. Nido-me niwa migi no kata yori kiri-sage taru ga, kore nitemo nao shini-taezu shite aru tokoro e, satobito-ra odorokite kaketsuke segare wo toriosae sugu-ni keisatsukan wo yobite watashi tari. Keikan ga mada bō wo mochite aru jidai no koto nari. Haha-oya wa otoko ga torae rare hikitate rarete yuku wo mite, taki no yōni chi no nagaruru naka yori, "Onore wa urami mo idakazu shinuru nareba, magoshirō wa yurushi tamaware" to iu. Kore wo kikite kokoro wo ugokasanu mono wa nakari ki. Magoshirō wa tochū nitemo sono kama wo furiage junsa wo oimawashi nado seshi ga, kyōjin nari tote hōmen serarete ie ni kaeri, ima mo ikite sato ni ari.]
Eleven: Perhaps because this woman had lived as a single mother and a single child, the relationship between his wife and her(mother-in-law) was strained, and his wife would often return to her parents' home and did not come back. That day, his wife was at home and bedridden( because she was not feeling well). Around noon, the son suddenly declared, "There's no way I can let gaga(my mother) live. I'm definitely going to kill her today," and brought out a large grass sickle, he began scrubbing it vigorously. Since his behavior did not seem like a joke at all, the mother apologized and tried to explain various reasons, but he would not listen. His wife got out of bed and too, tried to dissuade him while crying, but he refused to heed her at all. Then, seeing that the mother looked as if she might try to escape, he locked all the doors at the front and back of the house. Even when she said she needed to use the toilet, he brought a chamber pot himself and said, "Use this." When evening comes, the mother had finally given up, and she curled up beside the large Irori(sunken fireplace) and just kept weeping. The son approached her with the large sickle, which was sharply sharpened, in his hand. He swung it as if to mow, aiming for her left shoulder, but the tip of the blade caught on the Hidana(frame suspended over the Irori) and failed to make a clean slash. At that moment, the mother gave a terrified scream just like Yanosuke had heard in the deep mountain. On the second attempt, he slashed it down from her right shoulder, but even then she was still alive. Meanwhile, the villagers rushed over, gathered around, reined in the son, immediately called the police, and turned him over. This was back in the era when police officers still carried cudgels. Watching the man(her son) being arrested and led away, the mother, from in the blood flowing like a waterfall, said, "I will die without holding a grudge against him, so please forgive him." Nobody remained unmoved by hearing these words. Even as he was being led away, the son brandished the sickle and chased after the police officer(s), but he was released because he was a madman, returned home, and still lives in that village today.
Source: https://dl.ndl.go.jp/pid/767944/1/13
https://en.wikipedia.org/wiki/Irori
https://maps.app.goo.gl/nxmAkmPMe29qc6y46
https://www.youtube.com/watch?v=jGPTF3GupYA