Let H be the real quaternion algebra and Hm×n denote the set of all m × n matrices over H. For A ∈ Hm×n, we denote by Aφ the n × m matrix obtained by applying φ entrywise to the transposed matrix At, where φ is a nonstandard involution of H. A ∈ Hn×n is said to be φ-Hermitian if A = Aφ. In this paper, we construct a simultaneous decomposition of four real quaternion matrices with the same row number (A,B,C,D), where A is φ-Hermitian, and B,C,D are general matrices. Using this simultaneous matrix decomposition, we derive necessary and sufficient conditions for the existence of a solution to some real quaternion matrix equations involving φ-Hermicity in terms of ranks of the given real quaternion matrices. We also present the general solutions to these real quaternion matrix equations when they are solvable. Finally some numerical examples are presented to illustrate the results of this paper