We consider a wave equation with a nonlocal logarithmic damping depending on a small parameter 0 < θ < 1 2 . This research is a counter part of that was initiated by Charão-D'Abbicco-Ikehata considered in [5] for the large parameter case θ > 1 2 . We study the Cauchy problem for this model in R n to the case θ ∈ (0, 1 2 ), and we obtain an asymptotic profile and optimal estimates in time of solutions as t → ∞ in L 2 -sense. An important discovery in this research is that in the case when n = 1, we can present a threshold θ * = 1 4 of the parameter θ ∈ (0, 1 2 ) such that the solution of the Cauchy problem decays with some optimal rate for θ ∈ (0, θ * ) as t → ∞, while the L 2 -norm of the corresponding solution never decays for θ ∈ [θ * , 12 ), and in particular, in the case θ ∈ [θ * , 1 2 ) it shows an infinite time L 2 -blow up of the corresponding solutions. The former (i.e., θ ∈ (0, θ * ) case) indicates an usual diffusion phenomenon, while the latter (i.e., θ ∈ [θ * , 1 2 ) case) implies, so to speak, a singular diffusion phenomenon. Such a singular diffusion in the one dimensional case is a quite novel phenomenon discovered through our new model produced by logarithmic damping with a small parameter θ. It might be already prepared in the usual structural damping case such as (−∆) θ ut with θ ∈ (0, 1/2), however unfortunately nobody has ever just pointed out even in the structural damping case.