Gongtonggo

Classification and Dialects
Gongtonggo, translated to common language or lingua franca, is a creole of Japanese and Korean in a near future where both countries have merged to create one nation. Gongtonggo is mostly spoken in terretories that are under japo-korean reign, but are not native korean or japanese. Japanese and korean are both recognised as national languages besides Gongtonggo and it's not obligatory to learn Gongtonggo though most people do learn it as a second language in middle/highschool.

Most of the lexicon of Gongtonggo comes from (sino)japanese, with some words originating from (sino)korean. Most grammatical influences come from the korean language.

Phonotactics
The phonotactics of Gongtonggo are (C)(j)V(C), though j actually can be replaced by w in front of i and a ((C)(w)i/a(C)). Vowels that have a preceeding j are considered iotized.

allophones : l becomes ɾ intervocally s becomes ɕ before the vowel i or iotized vowels ts becomes tɕ before the vowel i or iotized vowels ɦ becomes ç before i or iotized vowels ɦ becomes h before any consonant or at the end of a word ɦ becomes ɸ before ɯᵝ

Soundchanges
Soundchanges can be found here

hangeul
for ones unfamiliar with hangeul, follow this link.

1 in initial position this graph is a zero consonant (or blanc) consonant, It is only /ŋ/ in final position.

the iotized versions of the vowels (except of /u/ and /i/, which have no iotized versions) are written with two small bars instead of one, like in hangeul. /ja/, /jɯᵝ/, /je/ and /jo/ are written as ㅑ, ㅠ, ㅒ and ㅛ respectively.

geminiate consonants /pp/, /tt/ and /kk/ can be written as ㅃ, ㄸ and ㄲ respectively.

Nouns
Nouns are isolating, their function in a sentence can be changed by the use of particles, these particles mostly imply case or relation.

Forming past tense
To form the past tense, the vowel syllable at the beginning of the suffix is replaced,  오 is  replaced by  잍. 이 and  애 by  일. 아 and  야 by  앹.

other functions
to form a negative, the word 브 (beu) or 블 (beul) (if the verb starts with a vowel) is put before the verb, in very formal texts this may be written as 不.

copula
To form a negative with the copula, the first i vowel that appears everywhere is replaced by a (written) but might be pronounced more towards e.