  An oscillating bound state is a phenomenon where excitations mediated by the
continuum modes oscillate persistently. Although it is generated by the
superposition of two bound states in the continuum (BICs), such phenomenon is
said to be unique to giant atoms. We present the phenomenon of an oscillating
bound state with an alternative waveguide QED system, which is a
one-dimensional semi-infinite waveguide coupled to a \textit{point-like}
quantum emitter. This \textit{point-like} quantum emitter is $\Lambda$-type
quantum system with one transition driven by a classical field.
