Okinawa, Japan - On Sunday, tens of thousands of people are expected to take part in what could become the largest anti-American military base rally in more than two decades on the Japanese island of Okinawa.



The recent alleged rape and killing of a 20-year-old Japanese woman by Kenneth Shinzato, a 32-year-old civilian employee of the Okinawa-based US Kadena Air Base, has reignited decades-long resentment among locals towards the heavy American military presence - and partly towards their own central government in Tokyo.

The sentiment dates back to more than seven decades ago, when 150,000 Okinawans - around one quarter of the island's population at the time - were killed in the fierce Battle of Okinawa, as the US tried to build a bridgehead to attack Japan's mainland towards the end of World War II.



"Ever since, America has kept their bases," Moriteru Arasaki, a professor emeritus of history at Okinawa University, told Al Jazeera.

"Over the 70 years of history, people's anti-base sentiment has been built up," added Arasaki, pointing out to the repeated crimes committed by US military personnel and employees based on the island.

Voices of Okinawa: Standing against a US military base

Even after Okinawa's reversion to Japanese sovereignty in 1972, which ended 27 years of US administrative rule, as much as one fifth of Okinawa's main island has been host to more than half of the 50,000 US troops stationed across Japan - Okinawa accounts for less than 1 percent of land mass of the entire country.

In the wake of a 1995 rally of some 85,000 people, triggered by the gang rape of a 12-year-old schoolgirl by three American servicemen, Washington and Tokyo announced the relocation plan of the US Marine Corps Air Station Futenma from the densely populated Ginowan to the relatively less crowded area of Henoko in the northern part of the island.



Yet, "subsequent crimes [have] made Okinawans now more determined", so as to oppose any US military presence in Okinawa, said Hiroji Yamashiro, of the Okinawa Peace Movement Center, which has been organising a daily protest at the Henoko base construction site.

'Very angry'

When I visited Henoko on Friday, more than 100 people were defying the scorching hot and humid weather to stage their 712th-day protest against the base construction.



With a semi-permanent protest camp set up just outside the base, the participants make speeches, chant slogans and occasionally attempt to block the entry and exit of vehicles out of the base.

READ MORE: Japan protests alleged rape by US sailor

With the growing anti-American base sentiment, a sense of betrayal towards Tokyo is also conspicuous, Yamashiro told Al Jazeera.

"Okinawa people are very angry at the Japanese government for putting so much of a burden on us and most of the Japanese people who ignore our situation."



This sentiment was re-confirmed in the outcome of the 48-seat prefecture assembly election earlier this month, in which candidates backing Governor Takeshi Onaga's efforts to block construction of the Henoko base formed a majority with 27 seats.



Onaga, elected as a governor on the back of a strident anti-base campaign in 2014, has been in a head-to-head clash with Prime Minister Shinzo Abe.



Sunday's planned rally will be "the climax of all the oppositions over many years. So, their demand will be stronger than ever," Arasaki said, adding that for the first time in such a rally protesters would be calling for the complete withdrawal of the US bases.



However, such a demand is highly unlikely to be accommodated both by Tokyo and Washington - Okinawa is located in a strategic location in the face of an increasingly assertive China in the East China Sea.



To counter the rise of China, the US has adopted a policy to pivot to Asia - and Tokyo and Washington know very well that they need each other, as seen in the ever-closer Japan-US alliance.