Manggahan High School (abbreviated as MHS; ), formerly known as Rizal High School Annex-Manggahan and mistakenly known as Manggahan National High School, is a public high school in Karangalan Village, Brgy. Manggahan, Pasig. History ANRRENN The site of Manggahan High School was once a private drug rehabilitation center called Anti-Narcotics Research and Reformation Network (ANRRENN). It was reported that the center was operating illegally and the National Housing Authority (Philippines) owned the lot. Because of these complaints, the operation of the center stopped and the NHA donated the lot to the city government of Pasig. S.Y. 1999-2000 of RHS Annex-Manggahan The first building (present-day V.P.E. I Building) was constructed in 1998 under the administration of Mayor Vicente P. Eusebio and inaugurated on May 29, 1999 by Rev. Fr. Jorge Jesus Bellosillo of Immaculate Conception Quasi-Parish (present-day Immaculate Conception Parish). Rizal High School Annex-Manggahan started to operate with Mrs. Nancy J. Tolentino as Head Teacher-in-charge. There were 430 first year and 210 second year, a total of 640 initial numbers of students who enrolled with 21 teachers. At the start of classes, the rooms were bare, no school decks, no blackboards. Some students brought their own stool for them not to squat on the floor. The needs of teachers and students were aired on television and printed on newspapers; thus, for the Department of Education, Culture, and Sports to provide the basic classroom facilities. S.Y. 2000-2001 of RHSAM Additional chairs and tables were received. Facilities and equipment were improved. Computers were forwarded through the initiative of Councilor Robert Eusebio (later became mayor). The office of the administrator was air-conditioned. The third year level was opened in S.Y. 2000-2001. By then, student population reached 1,033. As the student populace kept growing, there was a need for additional classrooms. S.Y. 2001-2002 of RHSAM In the year 2001, two new buildings, the SCE Building I and DPWH Building were constructed. This was the time when fourth year class was organized. The first batch of graduates received their diplomas. The commencement exercises were held at Rizal High School main campus with the graduates of other annexes. S.Y. 2002-2003 of RHSAM The construction of SCE II was started before the school year ends. The second commencement exercise was held at the school ground. It was the first commencement exercises outside the main campus. That year also marks the first valedictorian of the school. S.Y. 2003-2004 of