いは

ipa → iɸa → iwa. Compound of い (i, “emphatic marker”) and は (wa, “focus marker”). As -i was archaic even in Old Japanese, -wa was attached to supplement it.

いは • (iwa) 

1. emphatic nominative case marker
   • c. 759, Man'yōshū, (book 3, poem 237):

     不敢雖謂 話礼ゝゝ常 詔許曽 志斐伊波奏 強話登言

     INA TO₂ IPE₂DO₂ KATAre KATAre to₂ NO₂RASE ko₂so₂ sipi₂ i pa MAWOSE SIPI₂KATARI TO₂ NO₂RU

     Even though I said no, [she] keeps talking and talking. When [she] talks about sipï, I talk about compelling.

2. pronominal; person or thing; one
   • 797: Shoku Nihongi (edict 45)

     此乎持伊波稱乎致之、捨伊波謗乎招都

     KO₂ wo TAMOTU ipa TATAPE₂ wo ITAsi SUTURU ipa SOSIRI wo MANEKI₁tu

     To hold this is to praise it; to throw it away is to have had a bad mouth.

• いし (ishi)
• いも (imo)

• Kurano, Kenji (1936) Shoku Nihongi Senmyō (in Japanese), Tōkyō: Iwanami Shoten, →ISBN
• Satake, Akihiro; Hideo Yamada, Rikio Kudō, Masao Ōtani, Yoshiyuki Yamazaki (1999) Shin Nihon Koten Bungaku Taikei 1: Man'yōshū (in Japanese), Tōkyō: Iwanami Shoten, →ISBN

いは • (Iha) 

1. 伊波, 伊覇: a surname