Check if a given string is valid romaji Your program is given a string consisting entirely of lowercase letters at STDIN (or closest alternative). The program must then output a truthy or falsey value, depending on whether the input is valid romaji. 

Rules:


It must be possible to divide the entire string into a sequence of kana without any leftover characters.
Each kana can be a single vowel (aeiou)
Each kana can also be a consonant p, g, z, b, d, k, s, t, n, h, m, or r followed by a vowel. For example, ka and te are valid kana, but qa is not. 
The exceptions to the above rule are that zi, di, du, si, ti, and tu are not valid kana. 
The following are also valid kana: n, wa, wo, ya, yu, yo, ji, vu, fu, chi, shi, tsu. 
If a particular consonant is valid before an i (i.e ki, pi), the i can be replaced by a ya, yu, or yo and still be valid (i.e kya, kyu, kyo)
Exceptions to the above rule are chi and shi, for which the y has to be dropped too (i.e cha, chu, cho, sha, shu, sho)
It is also valid to double consonants if they are the first character of a kana (kka is valid but chhi is not)
Shortest answer wins. All regular loopholes are disallowed. 


List of all valid kana:

Can have double consonant:

ba, bu, be, bo, bi
ga, gu, ge, go, gi
ha, hu, he, ho, hi
ka, ku, ke, ko, ki
ma, mu, me, mo, mi
na, nu, ne, no, ni
pa, pu, pe, po, pi
ra, ru, re, ro, ri
sa, su, se, so,
za, zu, ze, zo,
da,     de, do,
ta,     te, to,
wa,         wo,
ya, yu,     yo,
    fu,
    vu
                ji

Can not have double consonant:

a, i, u, e, o, 
    tsu,
chi, cha, cho, chu,
shi, sha, sho, shu,
n


Test cases

Pass: 

kyoto
watashi
tsunami
bunpu
yappari


Fail: 

yi
chhi
zhi
kyi
Ruby, 96 149 bytes

Regex solution to match all the valid kana. Interestingly, "ecchi" is not valid according to the current rules, but perhaps it's for the best.



-&gt;s{s.gsub(/(?![dt]u)(sh|ch|([gbknhmrp])\2?y?|([zdst])\3?)?[auo]|(\g&lt;2&gt;)?\4?[ie]|(\g&lt;3&gt;)\5?e|ww?[ao]|n|tsu|([fv])\6?u|jj?i|j?y?[aou]|yy[aou]/){}==""}


Try it online! feat. Cruel Angel's Thesis