Mr Raihania is "outraged" that only 50 family members from this district's C Company are allowed to attend the closing of the association hui at Government House on December 1.
"When was someone going to come to Tairawhiti and consult us about our views? What about our whanau who have loved ones still lying over there? The widows who helped these men - crippled physically and mentally - back into society?
"The 28 is in our whakapapa. It is a part of us."
Mr Raihania said it was "incomprehensible" to close the doors on "the very men alive today who opened them".
"I can't help but think with sadness about all the little communities who gave money, kai and, of course, their precious boys to join the war effort.
"It is beyond belief a plan has been dreamed up to close the doors on them, especially when you consider the huge tautoko (support) at all events and the recent 24-hour Ngati Porou radiothon that raised $60,000 for the building of a museum to honour our soldiers. Something is not right here."
A Te Puni Kokiri statement said the founding members of 28 Maori Battalion Association voted to close their association earlier this year.
"The remaining veterans' vision was to leave their affairs in order when the association closed. This includes initiating a legislative process to protect how the logo and name are to be used in the future. This is now in progress."
Te Puni Kokiri said the 28 Maori Battalion get-togethers would continue at local RSAs without the rigid duties of running an association.
"Meetings, resolutions and 'point-of-order Mr Chairman' will be a thing of the past for these old soldiers - instead at their gatherings they will charge their glasses to fallen comrades."
Na Raihania is the son of Noel Raihania from Tokomaru Bay, a C Company veteran and chairman of the 28 Maori Battalion.
Mr Raihania senior said the decision to close the association was neither a one-man decision nor an easy one to make.
"I was against the closing at first, but when they put forward the reasons one had to think the decision to fold was a practical one.
"We are all koroua (old men). Rather than see it fade it away, we have decided to have one final hui and bring the association to a close with dignity. It seems more appropriate to do this than wait until the last man is gone.
"There are only 26 survivors left from the 28 Maori Battalion ranks and five C Company veterans.
"We are getting old. We are not the soldiers we used to be. It is sad to see us gradually fading away."
Te Puni Kokiri is footing the bill for the final celebration.
"We can't afford to run it ourselves, we haven't got enough money. I think our Auckland reunion a few years ago might have broken the camel's back."