On September 29, 2016, AH-Software tweeted that a VOICEROID+EX voicebank for Tohoku Kiritan and a VOCALOID4 update for Tohoku Zunko would be releasing on October 27 that year. The VOCALOID4 update for Zunko would only be a Natural voicebank, much like the SF-A2 miki V4 and the Kaai Yuki V4 packages before her. In addition, her voicebank would be available on its own or as a bundle with the VOCALOID4 Editor software.
A trial version of Zunko's VOCALOID4 voicebank was made available on October 14.
Almost all other traits of her vocal are "Average", with only a few standing out as unique to her vociebank.
Phonetic notes as noted:
She has issues with sounding as though she is rolling her tongue which can be corrected with VEL.
She may sound like she is re-singing sounds, this happens if you take sounds like "たー" ("ta") and add another vowel to make "た あー" ("Ta-a"). Even if the user divides the two sounds, this may not fix the problem and can be seen as annoying to work with.  The issue is with the "-" symbol. In Zunko's case, for some reason, it does not always register as a smooth transition from one sound to the next, instead separating the two sounds when it should sound like it is one.
Her "ラ" ("la") can be strong.
Software issues as noted:
Aside from GWL, there is no difference between the VOCALOID3 and VOCALOID4 versions and users may not rush to update her to the Vocaloid4 version for this reason.
This vocal will register for XSY, however this is a single release voicebank and there are no additional vocals included for her to utilize this function. Therefore users will have to purchase addition voicebanks not belonging to Zunko at all for use of XSY.
From Ver.4.3.0 of the VOCALOID engine onwards, a XSY group "AHS" was added to VOCALOID. All vocals within the "AHS" group can XSY with each other. This vocal release is part of this group. If a user owns one or more vocal releases within the "AHS" group, XSY between them will open up.
The "AHS" group is currently the second largest XSY group within VOCALOID, having a total of 14 voicebanks that can XSY with each other. If old versions that have since been re-released are removed, there are currently 12 unique voicebanks. These are: "Yuzuki Yukari Jun", "Yuzuki Yukari Onn", "Yuzuki Yukari Lin", "SF-A2 miki", "Tohoku Zunko", "Macne Nana", "Macne Petit", "Kizuna Akari", "Hiyama Kiyoteru Natural", "Hiyama Kiyoteru Rock", "Nekomura Iroha Natural" and "Nekomura Iroha Soft".
In total if a user was to own every VOCALOID3 and VOCALOID4 AH-Software vocal within the "AHS" group, this offers the equivalent of 182 additional voicebanks achievable via XSY. The total tone variation offered by the combined packages comes to a theoretical 196 voicebanks in total.
Note that also "GWL" does not become viable for use with any V3 vocals used as the primarily vocal. This should be considered when using any vocal for XSY within the "AHS" group from V3.
Also note that the updated vocals that brought a VOCALOID from VOCALOID3 into VOCALOID4 provided few differences, aside from adding GWL. Therefore these updates can provide little difference when used for XSY.
There is little point in XSY between Tohoku Zunko VOCALOID3 and VOCALOID4, as they have no differences between them and users are better with alternative partners for XSY within this group.