Five students from Martin Luther King Jr. Elementary School were honored yesterday by President and Mrs. Reagan when the First Couple returned to the White House from their 12-day trip to Tokyo.

The five received from Mrs. Reagan and then displayed for the welcoming crowd a colorful 12-foot-long mural of Tokyo painted by students at the Nagata-Cho Elementary School in Tokyo, sister school to Martin Luther King. The mural, showing gardens and multistory pagoda-style buildings, was a gift to the school in return for a mural of Washington that Martin Luther King students sent over with Mrs. Reagan.

"They gave to me some letters to be delivered to their sister school in Tokyo, and a mural," Mrs. Reagan told the crowd, "and they were very, very happy to receive them. And they sent back a lot of letters to you, and this mural . . . and they hope that this will be the beginning of a long friendship and relationship between the two schools."

William B. Dalton, principal of the Southeast Washington school, said Elana Gardner, 12, former student body president, had presented the Washington mural to the Reagans and so was one of the five chosen to receive the Tokyo gift.

The five also included Rodney Kelly, 13, and Len Barksdale, 13, who hadhelped to paint it, and Jeanette Hudson, 12, who was chosen for coming in second to Elana in the school spelling bee, Dalton said. All are in the sixth grade. The fifth student, Rudolph Hines, 8, a third-grader, is Reagan's current pen pal from the school.

Reagan and the First Lady shook hands with all five youngsters before greeting waiting cabinet ministers.

Dorothy Gray, building resources teacher at the King school, said 185 of its students were at the White House yesterday.